Unpublish a marketplace demo

Immediately unpublishes the marketplace demo. Returns **400** when the demo is already unpublished or the publish access record is not in an unpublishable status (for example `PENDING_UNPUBLISH`; use approve, deny, or cancel). **Required scopes (any one):** - `air:marketplace_demo_publish` (roles: `air_demo_manager`) **Additional permissions:** - Only members of the owning organization, Air admins, or SREs may perform this action on this marketplace demo.