As you can read in the FAQ, it is impossible to delete your account. They will give you some tips on how to leave it as empty as possible (but all your forum posts will remain online anyway): http://www.topix.com/topix/faq#delete_account
Because an account at Topix cannot be deleted, we suggest to make your data useless.
Be logged in on the site, then go to Profile Settings (Or Options, etc.). In all fields with personal data (such as name, address, city), fill in AccountKiller, if possible. If you can only choose from several options, change the value. If possible, use a homepage/URL field or long text field (such as Description) and put this line in it: http://www.accountkiller.com/removal-requested. This may incite webmasters to add an account deletion option.
If you can't find any contact info and still wish to ask something, for example a question about what exactly is deleted, about data retention, etc., you may contact the domain owners using this info.
If you signed up for Topix using a third-party login such as Facebook or Twitter, you probably want to revoke all access from Topix. Click the icon below to find out how.