You can change the email of your account by going to your account settings.
If you have used Google sign-in to sign up on miniExtensions, you'd need to click on the button named Unlink Google and use email instead.
You do not need to create a new account on miniExtensions. You would still use the same account you already have.
I unlinking Google does not work, the workaround is to use the forgot password from the login page.