Quote Originally Posted by katank
also, there's no way to raze a single level of the building.

I'd like that as even if you make the mistake of building say a fortress upgrade on top of that, you can rebuild quicker in time.

I think I had the same issue for the Krak when I built an upgrade on top of the citadel.
You can get rid of a single level of a castle by letting the AI invade and capture the province. Some buildings get destroyed, and sometimes th elevel of the castle gets dowgraded by one. It seems the chance of this happening is higher for forts and lower for fortresses. But I have had it happen once when I captured Const. from the Byzantines, their fortress turned into a citadel.