If you need to cancel

Unpaid, you can cancel yourself and the slot goes back; paid, the money has reached the tutor and a refund runs on their terms.

While a booking is unpaid you can cancel it yourself from its page, and the slot goes back to being available.

Once it is paid the cancel button is gone: the money has reached the tutor, and a refund runs on their terms rather than the platform's. Message the tutor first; if you cannot reach an agreement, open a dispute.