I think the CONTROL vs DELETE has to do with the type of stairs, theres two types with different stairs under those two types. To remove any stairs I have to first select the exact stairs (not just which type)
The stairs I had the most trouble deleting were the nasty green ones in the pre-built lots in the pleasantview n'hood (when I first started playing TS2) because I could not figure out what stairs they were
I couldn't delete those stairs even using "moveobjects on" Once I figured out which stairs they were (by selecting each kind) I was able to get rid of them without having to demolish the lot *laughs*
edit - ZZ beat me, takes me forever to get my thoughts together