I've been through this before and some posts 'came back'. The only way to be sure is to delete your account. If you really want an account just make a new one.
This was my experience using a Greasemonkey script some time ago. Some posts would "come back", and there were pockets years back it couldn't even find to delete, but were still accessible on my profile. Wound up just deleting my account and making a new one that I never, ever post on.