Reclamation campaigns are based on usage. If you're only trying to reclaim unused software, that's what you should use. If you want to remove all inventoried instances of the software, you would use retirement campaigns. If you want to upgrade all inventoried instances to a newer version, then you would use upgrade campaigns.
Anything expressed here is my own view and not necessarily that of my employer, Flexera. If my reply answers a question you have raised, please click "ACCEPT AS SOLUTION".