Unfortunately, you can't change your username at this time. You can, however, create a new user account, and then deactivate the old one. Here's how:
Create a new user account (at least User Administrator privileges required). Set the role to Author or Reviewer as required.
2. Add the new user as an owner to your projects. See this article for further details.
3. Deactivate the old user account.
If you have any questions, please contact Support.