Yes, it's possible.
You can cancel your booked session if more than 1 hour remaining.
You are allowed to cancel it without the penalty if more than 24 hours remaining.
However, you will have to pay the cancelation fee in order to cancel it when less than 24 hour remaining. You will be refunded partially after the penalty is deducted.
At least 24 hours before your booked session: 100% refund
Less than 24 hours before your booked session: 70% refund
Less than 1 hour before your booked session: Non-cancellable