As policy, accounts and posts are not deleted wholesale except in extraordinary circumstances as it destroys thread continuity. You have the ability to edit any post you have already made though, so you can already remove anything you've written in the backroom that you would prefer not be public. Any admin-level action beyond that will have to be cleared by the Forum Admins. I suggest you PM frogbeastegg, Secura, and Ser Clegane if editing isn't good enough for you.