From the FAQ
Can I Change my Username?
If you wish to request a username change, it will only be considered if:
* Your username consists of the number of children you have and you just had a change in that number. ex. dadof3kids --> dadof4kids
* You want your username to be the same as your business name ex. coolmom --> bluediaperstore
*Your username is your email address, for privacy reasons (must be the complete email, not just the prefix - i.e. firstname.lastname@example.org
would be changed but examplename would not)
*You have some outstanding reason why you need it changed - considered on a case by case basis.
*Keep in mind that your new username will come with a small line in your profile that says who you used to be.*
Please PM Juan M for username requests and allow a couple of days for the change to happen. Include your reason and your email address so that I can send you a response with your username change notification.