When you sign up for your hosting account you are asked to choose a username. Once you complete the order process, the username is saved in our system and it could not be changed later.
The main reason for this is that the username is used as the main ID value in our system. A record is created in our database for each new account and the username is used as a primary key. The primary key of a database is a permanent value that cannot be changed and thus the username cannot be altered as well.
In addition, the username is used in the file system on the server on which the account is located. This is the other main reason that makes altering of the username impossible.
You can, however, change the login password for your account at any time. For more details on changing the account password, please refer to this article: Changing the control panel (CP) password