To cancel or delete an event/s you click on Events.

Next step is to choose what events you want to delete or cancel. Then press delete and choose if you want to cancel the event or delete it. 

Cancel event: If you cancel an event players/Guardians are noticed that the event is cancelled and they can see it in their schedule. You can also put in a text and explain why the event or events are cancelled. 

Delete event: If you delete an event it just disappears from the schedule of player/guardian without any notice.