Admin
can change the username of a user. But in involves a huge lot of queries to run.
Which will even crash the DataBase.
So normally Admins don't change the username.
Below ywicky had a very long user name like
[email protected] or something like that. It was too long and as a result all the tables in the home page gets distorted when he posts something in a thread. That's why GT changed it by accepting the risk of crashing the DataBase.
Other than that GT will never change a username. It is really too risky. You might even lose all the posts, threads in the database.
So if you really don't like your current name, its better to create a new user account machang