I think, I have some more insights concerning the topic question now.
1) I'm afraid, you cannot delete your account if you are thinking of deleting all your replies, posts, started threads. These things will be present as long as the BEA will exist. Maybe another "meltdown" as it is said has occurred in the past, will have the same effect.
However if there are no new replies to your threads, threads will become obsolete, meaning will move to the end of the topic list as time goes by.
2) Due to my own trials (when quarreling with my registration), even your membername/password-combination will remain present for quite a while (at least 3 months, due to my experience).
3) Your membership can be revoked at CCBill.