I don't see what you mean. If I follow the links "User Control Panel -> Profile -> Edit account settings" I see no possible way to change the user name. Only email address and password.
Isn't this normal behaviour for forums and such places?
To be honest, I'd rather people did not change their usernames. I like some consistency. Even if the poster is basically anonymous. Else why not just post as a different user every visit?
Memory in C++ is a leaky abstraction .