If you are a coach or a player-coach, you can cancel an event (e.g. a friendly match canceled due to bad weather) and notify the players.
From the game sheet, click on the sprocket in the top right corner of the game info box and click on "Cancel Event". You can also access the cancel link directly from the "Schedule (calendar)" page, by going over to the relevant event and clicking the sprocket that appears to the right of the line.
Here are all the explanations in video.
ATTENTION : Deleting an event deletes all traces of it on SportEasy. This article talks about the cancellation of an event (for example, a friendly match canceled due to bad weather): the event remains visible in the calendar, with the mention "Canceled".