I don't know of a way to do exactly what you want. There are a few options though.
1) Send a PM to quark and ask him if he can change your username. You don't have too many posts right now but if you wanted to retain your post history but just change the user name this would be the first route I would suggest you attempt.
2) If you don't care about post history you could change the email address associated with your current account to a different email address that you control. If you don't have more than one email address it's pretty easy to make a new gmail address. That should free up your current email address so you could create a new account. To change your email go here: http://www.talkstats.com/profile.php?do=editpassword