You can do this at the Command Center. A player account can not be deleted if the player is in a team or league. An account may not be deleted in order to start anew. Each player must keep his acount.

*Warning*
The player account will irrevocably be deleted!
Gameaccount IDs will persist, will be locked and can not be re-registered.
*Warning*
If there are penalty points remaining on the account you won't be able to delete it. You can delete the account when the penalty points are removed.