Well, it somehow worked out for @pstrick1(?), but that was before the regime change. He had help from up high through; you yourself definitely can't do a thing - never could.
Back then, the policy was "no", except maybe for a valid reason, in rare cases. An example of a valid reason that had been accepted is someone that was relatively well know in a certain community and started here on another username, leading to confusion. IIRC, Kevin accepted to change the username to clear out that confusion. And invalid reason is "I don't like my nickname anymore".
