Unlink a supplier's amfori Site ID and tear down its synced data: clears the Site ID (blocking future auto-re-matching until a human re-links), HARD-deletes the supplier's amfori-synced audits, and HARD-deletes its amfori-synced findings — all in one transaction. Gated by the caller→supplier relationship: a brand with an active link may unlink; a supplier may NOT unlink its own link (403). Returns the refreshed supplier link resource.