Because actions are assigned to devices and monitors on an individual basis, actions can only be removed on the device- and monitor-level, and must be deleted from the Action Library. Additionally, if you have assigned action policies to your devices, you can remove the action from the policy itself.
When you remove an action from a device or monitor, the action still exists in the Active Monitor Library and is available for use with other devices and monitors. When you delete an action, you remove it from the database, and from all devices and monitors to which it is assigned; further, all report data related to the action is lost. Therefore, we recommend that you only delete an action when you are absolutely positive that you will not use it in the future, and feel that the related report data is not useful to your monitoring records.