Your email will still be linked to the account itself since there's two databases, one for the forum, one for the game.
You must clear the email used from your current account and add another one if you want it to be free for a new account you are about to make. In order to properly change your email for an already existing account, you need to log into the yellow box next to the banner, go into "user details" and modify the email field and save the changes. Then go into your profile and make sure it's changed there to.
Make sure you use a valid email when changing and also that the changes did take effect, once you've changed your email to another one you should be able to use the old email that now isn't linked to any account on a potential new one.
