Open Billing and click on Upgrade my plan > Cancel plan.
In case you're on the Free Trial and haven't subscribed to any of the paid plans, you won't be charged even after you have used all the free content upload hours. You're only required to add your credit or debit card when you wish to subscribe to a paid plan.
Feel free to contact us in case you have any questions about billing. We are happy to help out 🙂