Other than extraordinary circumstances, we don't mass delete user's posts/wipe accounts (although you are capable of editing your own posts, so if it's just for a couple specific things you posted, feel free to do it yourself). That being said, if you happen to have some special privacy issue for example, feel free to PM myself or another member of staff. Otherwise if you are just quitting the forums for whatever reason, logging out and not logging back in should be sufficient.