If you're going away for a period of time or similar and you want to prevent messages being sent out from your account, you can select the option to pause your scheduled messages under Manage > Preferences > Publishing Preferences.
Please see the following for more information:
When this is set to 'On', scheduled and queued messages will show as 'Sent' to prevent these being sent out in one go when you change this setting but will not be sent out from the backend of our system.
When you do want to have messages sent out from your account again, change this setting back to 'Off' and then re-schedule the posts.
Please note: This will need to be done individually for each user account.