Which term describes equipment or scenery that is no longer in use?

The correct term to describe equipment or scenery that is no longer in use is "decommissioned." This term specifically refers to items that have officially been removed from service or use, often in a formal or systematic way. Decommissioning suggests that there has been a decision made to retire the equipment or scenery, meaning it is no longer functioning or necessary for current operations.

In contrast, "active" refers to items that are currently in use. While both "dead" and "obsolete" might seem relevant, they imply different meanings. "Dead" typically pertains to something that is not functioning, but it does not necessarily mean it has been officially retired or deemed no longer useful. "Obsolete" refers to items that are out of date or no longer considered effective compared to newer alternatives, which does not always mean they are completely out of use. "Decommissioned" effectively captures the conclusion of use and the formal retirement of equipment or scenery.