Once a tournament has been published, to make any edits to that tournament, including cancelling the tournament, it will need to be done in the Control Center.
To cancel or postpone an event follow these steps:
Step 1: Log in to Control Center
Step 2: Find the approved tournament using the status filter 'approved'
Step 3: Click on the tournament you wish to edit. This will open the tournament. On the top right-hand side, click the drop-down Tournament actions box and choose Edit Tournament. 
Step 4: This will open up the Tournament - click Edit Tournament.
Step 5: In the Tournament name* - you can add 'canceled' or 'postponed' in front of the name.
and
For the registration date, you need to close the registration on yesterday's date. This will then prevent anyone from registering for the event. Edit the registration close date.
Step 6: Click Update Tournament
Step 7: You can click on Preview Tournament to check that the event is correctly updated and registration to the event is closed. 
To reverse this step, i.e. open it up again. You do the same, edit the tournament, update the name of the tournament and change the date of the tournament, and open for registration.
Note: The Tournament Director will be able to communicate and email any players that have registered for the Tournament through the players tab in the Serve Tennis account.