If you used a Premium plan but changed your mind, you can downgrade to a Free plan and use it as long as you need. You will still be able to use the service according to Free plan limits.
You can cancel your subscription on the Subscription page. Just hit the "Cancel Subscription" button and fill in a short survey.
If this option is unavailable in your account, please reach out to your account manager or our support team so we could help you.