To Enable/Disable any of the Automated Features (Campaigns, Feedback, Appointment Reminders, Reactivation Reminders) complete the following:

Go to the gear icon, at the top right hand side of your account > click the AUTOMATION page.

From there you can enable/disable all Automation or select each Automation that you want to enable or disable.

You can also choose the option "Enable On:". This will disable the selected Automation until your desired date to enable them back on.