The way we do things now, typically you can just report your own thread and for the report reason just type something like "please delete my thread." And typically the next mod/admin online will delete it for you.
We used to let users delete their own personal ad threads, edit their posts indefinitely, and delete their own posts indefinitely... but unfortunately the bad eggs had to spoil that for everyone else as they unfortunately found ways to skirt around the rules of the forum. So now you have to be a ZooVille Settler (150+ counted posts) to be able to edit and delete your own posts indefinitely.