How to delete a Hack This Site account?
The description of the service:
HackThisSite.org, commonly referred to as HTS, is an online hacking and security website. It aims to provide users with a way to learn and practice basic and advanced "hacking" skills through a series of challenges, in a safe and legal environment.
It is not possible to delete your Hack This Site account. The best you can do is delete any personal information that you have stored on their website.