It is not currently possible to edit user account names.
Allowing user name changes is no small feature, as it would require major back-end modifications and demand that we also rework several security measures.
So far it has been our belief that our limited resources would be better invested in expanding and improving the game itself.
If we ever decide to add the option to request name changes, we will most likely make an announcement on our news blog or our community forum.
However this is not a planned feature at the moment.