A yogi can always cancel for a class, depending on the cancellation term. After cancelling, the credit will automatically be credited to the membership or class pass from the yogi.
If the yogi wants to cancel class after the cancellation term, the yogi will see this is not possible and the credit for this class will not be returned. As a teacher you can delete a yogi from the class list, by doing this, the credit will be returned.
If there is a restriction on a membership, such as one class per week, this class can not be booked by the yogi in a following week. The cancelled class must be followed in the current week of this cancelled class. As a teacher you can add a yogi to a class in the next week upon request.