You can cancel or change your subscription from the 'Account' tab of the Account Dashboard. First scroll down to 'Account' and then click the 'Cancel Subscription' or 'Change' buttons. If you are on a free 30 day trial your account will immediately revert to a 'Free Account'.


Here is a guide to Canceling your Subscription:

https://www.quiz-maker.com/Quiz-Help/Cancel-Subscription