To cancel one or more bookings on an event, open the event and change the status of the bookings to a cancelled status.
Cancelling a booking is simply changing the status of the booking to a 'cancelled' status. Bookings in a cancelled status no longer block the space held by the booking(s). To cancel an entire event, simply cancel all of the bookings for the event.
Once a booking is cancelled, there is no further action required, such as, deleting the booking. Cancelled bookings remain in the system for reporting purposes.