Go to your settings page and scroll down to the section called 'your subscription'. Here you can cancel your current subscription or reactivate a canceled one.
(Note that you need to be logged in to see this page).
You can cancel the subscription at anytime within the Free Trial and you will still have access to the Free trial.
If you do not have an active subscription then you have another account, perhaps one with Google or Facebook login that you have recently changed email on.