Take a single class off the timetable from the calendar.
Needs the Manage bookings permission.
Cancel only appears on classes that can still be cancelled. If it is missing, the class has already run or has already been cancelled.
Cancelling does not refund or message anyone by itself. Deal with the people booked on it first, under Clients, then Bookings.
If the class is synced to Urban Sports Club, the menu carries a separate Cancel in Urban as well.
Cancelling does not cancel the bookings on the class. The people booked stay booked, which is why they have to be dealt with rather than left.
There is no button to undo a cancellation. If you cancel one by mistake, ask the assistant to put it back.