Change my username
It is not possible to change your username at this time. Good news is you can create another account with a different username and fork all your public projects.
If you want to fork your Private projects, without editing their privacy settings, please check this article.
Change my email address
If you want to change the email address associated with your Animator account, you need to go to https://account.haikuforteams.com/ and log in.