You post a request at the following link, requesting your account be deleted. http://www.speedrun.com/The_Site/thread/frjsy
And you can't really say the admin aren't responsive, considering you haven't posted a request on the board yet.
Also, I'm editing to add in that there are rules about which accounts can be deleted. The account can't have had any posts or runs posted in a year, and the account has the remain inactive for that period of time as well. Your last post before seeking deletion was around seven months ago. I have no clue about being otherwise inactive. I also don't know if special exceptions are made, but the only real way to find out is to post on that board all the same.
That's not exactly it. The rule that says "Usernames won't be deleted unless the account has no posts/runs and has been inactive for over a year." is in case you want your account to be renamed to an already existing username. If you just want your own account deleted you can do it whenever you want.