The common advice for this and many similar issues with hn is to email pg and ask him to delete your account, unban you, or give you a pony. Whether you consider this an acceptable solution is another question.
I imagine pg has more pressing matters to deal with. Better email info@ycombinator.com instead if you need something deleted. A YCombinator employee confirmed to me recently that this is the address to contact in case you absolutely have to, so it obviously shouldn't be abused.
I think there are other admins besides PG. I don't know who they are or how many there are.