Can't build new residential building

If you destroy a residental area, you cannot get a new slot for them, like how factories and stores work. The only thing that will happen is that your population will decrease. If you want to destroy a building because you want to place it in a new place, then you should move the building.

If you have used up your available building icon, and you want to create a new building (zone actually), you will need to upgrade one of the zones (empty lots) with a building. Then only you will get an additional building/zone available for you to create/place.