As far as I know if you're a contractor working on an abandonment project it's standard contract language unless amended by the customer that anything removed as part of the abandonment project becomes the property of the contractor for disposal as they wish.
I work in healthcare. In both facilities and cable plant we refer to it as "demolition". We specifically amend the contract to say what items removed will be retained by the owner (usually fixtures, ceiling tile, tv mounts, intercom stations, etc we can reuse elsewhere) and the contractor has rights to the rest. Normally if you don't specify, the "salvage rights" belong to the contractor.