How do I disable sending scheduled messages automatically?

Go to the Scheduler page on the top menu.
Click Edit under Actions on the right, and select the message you would like to disable.
Set Days Before/After to Do Not Send.

Once created, this message will show on the Guest Reservations page.

Note: If the message is set to active and the send rule is set to Do Not Send, then the message will appear on the Guest Reservations page and you will be able to manually send the message.