Changing your username is possible, but requires an effort on the part of our Support Team. Open a support ticket following these steps.
Login to the Support Center (found by selecting the headset button in the upper-right menu)
Click Open a Support Ticket.
Select Login Problems under Ticket Subject.
Under the Domain Name drop-down, click any of your listed domain names. You may also select "Other" and enter "user.name" in place of a domain name.
In the Problem Description field, please list the username you wish to use.
Please allow up to two business days for a response.