There is a "delete my account" in your control Panel. And they give you 72 hours to change your mind if needed. Then after that, you can get a new hosting name.
It will only cancle your hosting name and delete everything in it. But NOT your forum or Control Panel account.
I just cancled mine too for the same reason as you. I sent a request in the comment field box asking that I'd rather change my hosting name without having to delete my account., we'll see if thats allowed, but if the request can not be done it's ok, I can wait for 72 hours to get a new name.