On each Menu Item there is an Active Button. If you turn this Active Button off, the Menu Item is now Deactivated.
If you are trying to search for this Menu Item in your Item Library and the Menu Item has been Deactivated, then you will need to Include Inactive Items in your Item Library Search.
To include Inactive items in your search, scroll to the end of your Item Library and select Include Inactive Items and search again in the FIND box.
See also How to Search the Item Library