If you’re able to log in at https://www.brillianttv.com/ on a web browser, you can change your login email address at any time under edit profile.
Click on the user icon in the top right hand of the screen:
You can also change your display name, profile picture, and request a password reset here too!
Don't forget to click Save on the bottom of the page to save your changes.
If you are unable to login, please see: How do I sign in to my membership?