Hi, unlinking accounts is currently only possible for Game Advisors. Please contact one of them via live chat or phone at https://help.ea.com/contact-us for further assistance.
Also on a general note, you should not create a new account, all your game entitlements are tied to your account and by simply changing to a new account you might lose access to all your previous games. If the email address for your account is no longer in use, you can get it changed to a new one by contacting a Game Advisor.
In this case I would strongly suggest to get the email address of your old account changed to a new one, instead of continue playing with the newly created Origin account.
