Deletes a survey and everything beneath it — collected responses and answers, recordings, translations and questions — then removes its call routing. This cannot be undone, and the responses already collected are gone with it. A survey a call flow still points at is refused with 409 and left untouched, so the reference check runs before anything is deleted. Cleanup afterward is not transactional: a failure removing a recording or the call routing is tolerated and still returns 200.