Packages, Add-ons, Systems, and Stand Alone Equipment are all considered resources and can be configured to be "Active" or "Inactive".

An Active resource can be assigned to upcoming events. An Inactive resource will not appear on the drop-down menus when you add a new event. This setting has no other effect on the application.  

Keep in mind, if a resource is assigned to an event, changing it from Active to Inactive will NOT delete the assignment. You will have to manually edit each event and remove the resource on the Edit Event pages.

The purpose of this setting is to allow you to disable equipment that is no longer in use...and therefore do not want to appear as an option when assigning resources.