How to best remove units?

[RaZor HeaD]

There are a few units in the game which I find to be quite ridiculous.

Mounted Longbowmen...like someone with a 6' bow could ride a horse well, let alone shoot the bow.
Elephants with cannons on their back...like a cannons recoil wouldn't simply snap an elephants back the first time it was fired.

I was wondering, what is a good method for removing said units from the game?
If you delete the entries for them from the export_descr_unit file will that screw up anything else, like the computers AI for building units? Or should you go into the export_descr_buildings file and delete the units there? Or do both things?

[konny]

It would be sufficient to remove them from export_descr_buildings (and the mercenary file, descr_strat and campaign_script, if they happen to appear there). That way no one would be able to create them and they simply wouldn't appear in game.

Removing them from EDU is not needed.

[Caesar Clivus]

You might also need to remove them from descr_rebel_factions.txt and descr_sm_faction.txt (if the faction that owns them can horde).