Hi there,
Currently, there is no documentation for it.
If you disable(unpublish) the status of the selected alert, the selected alert will not be working.
If you disable the default email and default system of the selected alert, the selected alert will be disabled by default on the frontend
http://take.ms/NRuwa7 but this affects on the new registered users only. If you want to affect all the users, you can select 'Toggle Default Email' and 'Toggle Default System' for the selected alerts.
If you disable the Allow Modify Email and Allow Modify System of the selected alert, the selected alert will not be able to adjust by the users on the frontend
http://take.ms/DZvId. The 'Toggle Allow Modify Email' and 'Toggle Allow Modify System' work the same way but it is to affect more than 1 selected alerts in one go.