There is a decision named 'Megali Idea' which gives you cores over Izmir and Bursa (I hate those names, real names are Smyrna and Prusa/Nikaea). It also gives you cores over Thrace.
So what I did was to take Smyrna and Prusa regions in one war with help from Russia. Until this point, taking Thrace is not possible. I also made them release all of their vassals. Then I declared another war for Thrace, and this time I won by myself. The Ottoman capital automatically moved to Ankara.
Then I simply took the Konya region (again, I hate Turkish names based on Greek names, it is actually Iconium region). Then came the grand decision of 'Kings of the Kings' and I clicked on it. Byzantium formed, and Ottomans still live.