please delete everything

You can't. That the name of the game

Deleting

I don't know how to delete your account altogether, but you can delete all the information on your profile and any pictures you've posted. You can also make your profile private so nobody can view it. Just go to the "User CP" link on the top left of the toolbar at the top of the page and then select the appropriate edit functions on the left side of the page.

Slight misconception there, "private" simply makes it impossible to tell if you are logged on or not, it does not hide your profile.
Accounts cannot be deleted only banned, posts can sometimes be deleted by contacting a moderator for assistance.

You might consider just asking to have your profile renamed. It might be enough, and it's a lot easier for mods.