Finding and Viewing Cancelled Bookings
Finding cancelled bookings is not a difficult job, and there are a number of options depending on the business goals. You can Search for a booking on it's confirmation number, as that confirmation never changes and a booking in cancelled status will show.
Because each cancellation produces a 'cancellation number', read: "Canceling a Booking and Using Cancellation Numbers" at: https://support.bookingcenter.com/index.php?/Knowledgebase/Article/View/508
You can also use the 'Cancellation' report which will allow you to search for bookings that were cancelled on a specific date or had an arrival date and are in status: cancelled (a quick way see who, on a given day, were coming but had cancelled).
Finally, you can use the Booking Production report, though the cancellations listed here are based on the date the booking was booked, not cancelled. Read: https://support.bookingcenter.com/index.php?/Knowledgebase/Article/View/452 for more details on this subject.