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.
If unlinking Google does not work, the workaround is to use the forgot password from the login page.