If an Agreement is no longer valid or required, then it can be deactivated. This will not delete it but it will add it to a list of Inactive Agreements within your views. It can be re-activated.
To deactivate, go to the ribbon of the record:
It will ask for a reason to be selected:
It will list the appropriate Inactive Views:
Will this affect any current live linked Placements?
No. Current placements that the Agreement is linked to will not be affected. It simply cannot be used for any new placements.