If you want to cancel a booking, simply move the mouse over the booking without click on it and you'lle see a window with some info on it and some buttons as well. Press the cancel button to cancel the court booking.

Then you'll see a window where you can select a reason why the court booking is cancelled, also you can write some notes about it, and decide if you're gonna give the moneyh back to the customers or not.

Once you have decided all this press Cancel and it will be done.