Once you get your VMK name, you can't change it. You can create a
different character, but it might not have the name you want available.
VMK sometimes approves a name that has to be changed later. (MommyKate
had to change her name because of the Mommy part.) VMK will reset the
name function.
You can always try to use the Contact Us link on the bottom of the VMK
home page to ask them to reset your character name, but they may or
may not do it. It can't hurt to ask.