You can change your account's email by going to the 'Account' section of your account settings. Follow the link or select the option from the dropdown menu on your profile icon:
Scrolling down you'll find the options to Change the Email and Reset Password.
Google Sign-in
If you have used Google sign-in to sign up on miniExtensions, you'd need to click on the button named Unlink Google account under the login method section. Follow the link for a step-by-step guide.
💡Note
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 option from the login page.