If you are a coach or a player-coach, you can postpone an event from the game sheet by clicking on the gear in the upper right corner of the game info box and then on "postpone".
You can then:
- Set the new date or choose "postpone to an unknown date"
- Tick "notify players" to inform them of the postponement (via email and / or smartphone notification)
- Tick "Reset the player's availabilities" if the call-ups had already been sent for the old date.
You can also access the postpone link directly from the "schedule (calendar)" page, by going to the relevant event and clicking on the sprocket that appears to the right of the line.