I have more housing than colonist, but I have homeless people, and colonists also complaining about homelessness. Maybe they prefer to live in smaller buildings, or something like this?
If you destroy a housing structure it will make the people inside homeless and while continue to be homeless whether or not you have space, use a fire drill when you get one
Just your average MyColony player....
From my experience; Every time I have destroyed a housing unit the colonists will instantly occupy any empty housing. If there is none then they will of course become homeless.
I try to sell smaller buildings very slowly, I don't think that is the issue