Usernames
Given permission to edit your user account, you may change your username once every two weeks from the user settings area. Username changes are free. Usernames are unique, so you cannot use a name already in use by another user. Usernames are only allowed to contain alphanumeric characters, plus dashes and underscores.
Warning
During the two week cooldown period, your previous username is reserved and you can switch back to it at any time. Nobody else can use your previous username during this time.