Pretty self explanatory. I can't seem to find a way to demolish a settlement after it's been built. There has to be a way I could have sworn I saw it once...
I still don't understand why anyone would destroy a settlement that provides resources for you? Even if it's a new settlement that has nothing, it's functional utility as a teleportation hub, caravan node, and item-shop post are great even if you use it for nothing else.
Why destroy something that can only help you?
In this particular game there's no benefit for raizing. I'm all for Attila the Hun, but I'm all for having an advantage that moves me to victory faster even more, and acquiring AI settlements with workshops, libraries, etc .. these things can only help you by adding to your knowledge & resource base. A lot of times my best producing cities are the large AI citiies I capture, since I put a priority on combat unit construction over buildings.