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I think somewhere in the yoworld.com posts the vikings said we might have this option in the future. so hopefully the people that want this feature get it
Zynga would delete your houses if you emptied them and told them exactly which house it was. I had them delete 6 homes for me a while ago. There is no undo though, so I don't think they wanted to do it too often.
There is no way to do this as of now. I recieved a reply on this issue from BVG about it, and they said that they are looking into it and a feature like this may come, but it would cost a coin amount to remove them, if i remember correctly they said 600c each house.