Canceling & unsubscribing can be done from your Rafflecopter account with just a few clicks! Sign into your Rafflecopter account, find your account settings, click 'Your Subscription', scroll to the very bottom of the page & you'll find an area called 'downgrade subscription'. View the screenshot below for a visual.
Once you unsubscribe, you'll have access to premium features until your billing cycle comes to a close. Your Rafflecopter account will not be able to access to the paid features once your billing cycle expires, but you can always upgrade again at a later date.