For now, instructors are only able to delete unbooked lesson slots or “instant book” slots that do not yet have a student registered.
If you set up an instant book slots but are no longer available for that date and time, you can cancel that slot by first going to your instructor dashboard (https://www.rec.us/app/instructor-profile) and then finding the lesson under My Schedule.
Click on the row with the lesson you want to delete to pull up the booking detail page. Once on the booking detail page click Cancel Lesson Slot and the slot will be removed.