In custom battle or campaign? For custom battle look in export_descr_unit for the unit you want to delete (Axemen of Lossarnach for example)
Code:
type Axemen of Lossarnach
dictionary Axemen_of_Lossarnach ; Axemen of Lossarnach
category infantry
class heavy
voice_type Heavy
banner faction main_infantry
banner holy crusade
soldier Varangian_Guard, 60, 0, 1
officer gondor_captain_early_flag
officer gondor_captain_early_flag
mount_effect horse +1, camel +1, elephant -4
attributes sea_faring, hide_forest, hardy, can_withdraw, free_upkeep_unit, no_custom
formation 1.2, 1.2, 2.4, 2.4, 4, square
stat_health 1, 3
stat_pri 8, 6, no, 0, 0, melee, melee_blade, slashing, axe, 50, 1
stat_pri_attr ap
stat_sec 0, 0, no, 0, 0, no, melee_simple, blunt, none, 0, 1
stat_sec_attr no
stat_pri_armour 6, 4, 0, metal
stat_sec_armour 0, 0, flesh
stat_heat 2
stat_ground 0, -1, 0, -2
stat_mental 13, normal, trained
stat_charge_dist 15
stat_fire_delay 0
stat_food 60, 300
stat_cost 1, 470, 200, 75, 75, 470, 3, 150
armour_ug_levels 1, 2
armour_ug_models lossarnach, lossarnach_ug1
ownership sicily
era 0 sicily
era 1 sicily
era 2 sicily
recruit_priority_offset 5
Add the part in red.
For the campaign, look in export_descr_building for all recruitement lines of the unit
Code:
town_guard city requires factions { sicily, byzantium, milan, scotland, turks, spain, venice, england, france, hre, portugal, egypt, mongols, moors, }
{
convert_to 2
capability
{
recruit_pool "High Sword" 1 0.2 2 0 requires factions { egypt, } and region_religion orthodox 33 and hidden_resource forest
recruit_pool "High Sword" 1 0.1 1 0 requires factions { egypt, } and region_religion orthodox 33 and hidden_resource grasland
recruit_pool "High Sword" 1 0.05 1 0 requires factions { egypt, } and region_religion orthodox 33 and hidden_resource mountains or hidden_resource desert
recruit_pool "Lindon Longspears" 1 0.05 1 0 requires factions { egypt, } and hidden_resource lindon
recruit_pool "Silvan Spear" 1 0.15 2 0 requires factions { mongols, } and region_religion orthodox 33 and hidden_resource forest
recruit_pool "Silvan Spear" 1 0.07 1 0 requires factions { mongols, } and region_religion orthodox 33 and hidden_resource grasland
recruit_pool "Silvan Spear" 1 0.04 1 0 requires factions { mongols, } and region_religion orthodox 33 and hidden_resource mountains or hidden_resource desert
recruit_pool "Silvan Sword" 1 0.15 2 0 requires factions { mongols, } and region_religion orthodox 33 and hidden_resource forest
recruit_pool "Silvan Sword" 1 0.07 1 0 requires factions { mongols, } and region_religion orthodox 33 and hidden_resource grasland
recruit_pool "Silvan Sword" 1 0.04 1 0 requires factions { mongols, } and region_religion orthodox 33 and hidden_resource mountains or hidden_resource desert
recruit_pool "Miners" 1 0.15 2 0 requires factions { moors, } and region_religion islam 25 and hidden_resource mountains
recruit_pool "Miners" 1 0.05 1 0 requires factions { moors, } and region_religion islam 25 and hidden_resource forest or hidden_resource grasland
recruit_pool "Miners" 1 0.03 1 0 requires factions { moors, } and region_religion islam 25 and hidden_resource desert
recruit_pool "Dwarven Warriors" 1 0.15 2 0 requires factions { moors, } and region_religion islam 33 and hidden_resource mountains
recruit_pool "Dwarven Warriors" 1 0.05 1 0 requires factions { moors, } and region_religion islam 33 and hidden_resource forest or hidden_resource grasland
recruit_pool "Dwarven Warriors" 1 0.03 1 0 requires factions { moors, } and region_religion islam 33 and hidden_resource desert
recruit_pool "Dismounted Kofm" 1 0.2 3 0 requires factions { sicily, } and region_religion numenorian 25 and hidden_resource grasland
recruit_pool "Dismounted Kofm" 1 0.1 2 0 requires factions { sicily, } and region_religion numenorian 25 and hidden_resource forest
recruit_pool "Dismounted Kofm" 1 0.05 1 0 requires factions { sicily, } and region_religion numenorian 25 and hidden_resource desert or hidden_resource mountains
; recruit_pool "Axemen of Lossarnach" 1 0.2 2 0 requires factions { sicily, } and hidden_resource lossarnach
recruit_pool "Marines" 1 0.15 2 0 requires factions { sicily, } and hidden_resource pelargir
recruit_pool "Desert Spearmen" 1 0.2 2 0 requires factions { spain, } and region_religion catholic 25 and hidden_resource desert or hidden_resource grasland
recruit_pool "Desert Spearmen" 1 0.1 1 0 requires factions { spain, } and region_religion catholic 25 and hidden_resource forest or hidden_resource mountains
recruit_pool "Corsairs" 1 0.2 2 0 requires factions { spain, } and hidden_resource coast
recruit_pool "Southron Spearmen" 1 0.2 3 0 requires factions { spain, } and region_religion catholic 33 and hidden_resource desert or hidden_resource grasland
recruit_pool "Southron Spearmen" 1 0.1 2 0 requires factions { spain, } and region_religion catholic 33 and hidden_resource forest or hidden_resource mountains
recruit_pool "militia" 1 0.2 2 0 requires factions { milan, } and region_religion northmen 25 and hidden_resource grasland
recruit_pool "militia" 1 0.1 1 0 requires factions { milan, } and region_religion northmen 25 and hidden_resource forest
recruit_pool "militia" 1 0.05 1 0 requires factions { milan, } and region_religion northmen 25 and hidden_resource desert or hidden_resource mountains
recruit_pool "Rohan Axemen" 1 0.2 2 0 requires factions { milan, } and region_religion northmen 33 and hidden_resource grasland
recruit_pool "Rohan Axemen" 1 0.1 1 0 requires factions { milan, } and region_religion northmen 33 and hidden_resource forest
recruit_pool "Rohan Axemen" 1 0.05 1 0 requires factions { milan, } and region_religion northmen 33 and hidden_resource desert or hidden_resource mountains
recruit_pool "Balchoth Horde" 1 0.2 3 0 requires factions { venice, } and region_religion catholic 25 and hidden_resource desert or hidden_resource grasland
recruit_pool "Balchoth Horde" 1 0.1 2 0 requires factions { venice, } and region_religion catholic 25 and hidden_resource forest or hidden_resource mountains
recruit_pool "Easterling Clansmen" 1 0.2 3 0 requires factions { venice, } and region_religion catholic 33 and hidden_resource desert or hidden_resource grasland
recruit_pool "Easterling Clansmen" 1 0.1 2 0 requires factions { venice, } and region_religion catholic 33 and hidden_resource forest or hidden_resource mountains
recruit_pool "Watchmen" 1 0.2 3 0 requires factions { scotland, } and region_religion northmen 25 and hidden_resource grasland
recruit_pool "Watchmen" 1 0.1 2 0 requires factions { scotland, } and region_religion northmen 25 and hidden_resource forest
recruit_pool "Watchmen" 1 0.05 1 0 requires factions { scotland, } and region_religion northmen 25 and hidden_resource desert or hidden_resource mountains
recruit_pool "Dalesmen" 1 0.15 2 0 requires factions { scotland, } and region_religion northmen 33 and hidden_resource grasland
recruit_pool "Dalesmen" 1 0.07 1 0 requires factions { scotland, } and region_religion northmen 33 and hidden_resource forest
recruit_pool "Dalesmen" 1 0.04 1 0 requires factions { scotland, } and region_religion northmen 33 and hidden_resource desert or hidden_resource mountains
recruit_pool "Dale Woodsmen" 1 0.15 2 0 requires factions { scotland, } and hidden_resource dale_rivers
recruit_pool "Arnor Militia" 1 0.2 3 0 requires factions { byzantium, turks, } and region_religion numenorian 33 and event_counter dunedain_turks 1 and hidden_resource grasland
recruit_pool "Arnor Militia" 1 0.1 2 0 requires factions { byzantium, turks, } and region_religion numenorian 33 and event_counter dunedain_turks 1 and hidden_resource forest
recruit_pool "Arnor Militia" 1 0.05 1 0 requires factions { byzantium, turks, } and region_religion numenorian 33 and event_counter dunedain_turks 1 and hidden_resource desert
recruit_pool "Arnor Militia" 1 0.05 1 0 requires factions { byzantium, turks, } and region_religion numenorian 33 and event_counter dunedain_turks 1 and hidden_resource mountains
recruit_pool "Breeland Militia" 1 0.25 2 0 requires factions { turks, } and region_religion northmen 25 and event_counter northmen_turks 1 and hidden_resource grasland
recruit_pool "Breeland Militia" 1 0.125 1 0 requires factions { turks, } and region_religion northmen 25 and event_counter northmen_turks 1 and hidden_resource forest
recruit_pool "Breeland Militia" 1 0.06 1 0 requires factions { turks, } and region_religion northmen 25 and event_counter northmen_turks 1 and hidden_resource desert
recruit_pool "Breeland Militia" 1 0.06 1 0 requires factions { turks, } and region_religion northmen 25 and event_counter northmen_turks 1 and hidden_resource mountains
recruit_pool "Snaga Band" 1 0.2 3 0 requires factions { portugal, } and region_religion catholic 25 and hidden_resource mountains
recruit_pool "Snaga Band" 1 0.15 2 0 requires factions { portugal, } and region_religion catholic 25 and hidden_resource grasland
recruit_pool "Snaga Band" 1 0.1 2 0 requires factions { portugal, } and region_religion catholic 25 and hidden_resource forest or hidden_resource desert
recruit_pool "Goblin Spears" 1 0.2 3 0 requires factions { portugal, } and region_religion catholic 33 and hidden_resource mountains
recruit_pool "Goblin Spears" 1 0.15 2 0 requires factions { portugal, } and region_religion catholic 33 and hidden_resource grasland
recruit_pool "Goblin Spears" 1 0.1 2 0 requires factions { portugal, } and region_religion catholic 33 and hidden_resource forest or hidden_resource desert
recruit_pool "Orc Band" 1 0.2 3 0 requires factions { england, } and region_religion catholic 25 and hidden_resource mountains
recruit_pool "Orc Band" 1 0.15 2 0 requires factions { england, } and region_religion catholic 25 and hidden_resource grasland
recruit_pool "Orc Band" 1 0.1 2 0 requires factions { england, } and region_religion catholic 25 and hidden_resource forest or hidden_resource desert
recruit_pool "Mordor Orcs" 1 0.25 3 0 requires factions { england, } and region_religion catholic 33 and hidden_resource mountains
recruit_pool "Mordor Orcs" 1 0.2 2 0 requires factions { england, } and region_religion catholic 33 and hidden_resource grasland
recruit_pool "Mordor Orcs" 1 0.125 2 0 requires factions { england, } and region_religion catholic 33 and hidden_resource forest or hidden_resource desert
recruit_pool "Dunlendings" 1 0.15 2 0 requires factions { france, } and hidden_resource dunland
recruit_pool "Dunlending Axemen" 1 0.1 1 0 requires factions { france, } and hidden_resource dunland
recruit_pool "Uruk-Hai Raiders" 1 0.2 3 0 requires factions { france, } and region_religion catholic 33 and hidden_resource mountains
recruit_pool "Uruk-Hai Raiders" 1 0.15 2 0 requires factions { france, } and region_religion catholic 33 and hidden_resource grasland
recruit_pool "Uruk-Hai Raiders" 1 0.1 2 0 requires factions { france, } and region_religion catholic 33 and hidden_resource forest or hidden_resource desert
recruit_pool "Snaga Skirmishers" 1 0.15 3 0 requires factions { hre, france, } and region_religion catholic 25 and hidden_resource mountains
recruit_pool "Snaga Skirmishers" 1 0.1 2 0 requires factions { hre, france, } and region_religion catholic 25 and hidden_resource grasland
recruit_pool "Snaga Skirmishers" 1 0.07 2 0 requires factions { hre, france, } and region_religion catholic 25 and hidden_resource forest or hidden_resource desert
recruit_pool "Goblin Orcs" 1 0.2 3 0 requires factions { hre, } and region_religion catholic 33 and hidden_resource mountains
recruit_pool "Goblin Orcs" 1 0.15 2 0 requires factions { hre, } and region_religion catholic 33 and hidden_resource grasland
recruit_pool "Goblin Orcs" 1 0.1 2 0 requires factions { hre, } and region_religion catholic 33 and hidden_resource forest or hidden_resource desert
law_bonus bonus 2
recruits_exp_bonus bonus 1 requires event_counter is_the_ai 1
}
material wooden
construction 5
cost 3200
settlement_min large_town
upgrades
{
city_watch
}
}
This is the second barracks level for a city, you should add the part in red again (do that for ALL barracks levels from city and castle where the unit is recruitable). The part in blue indicates which unit the recruit pool is for 
I hope this helps you!