Ducati916: sure there is....OOOOOPS......don't go there Duc.....
just kidding Pizza.... ;-)
You rascal! ;)
It may be worth mentioning that you can disable your current account and then create a new one with a different name - however this is not "changing your user name".
P.S - if you do not disable your existing account before creating a new account, you are multi-accounting, and both (all) of your accounts may be disabled if discovered.
Stay classy,
-WGTpizza