Idempotent: deleting an already-deleted handle answers 200 as well. Unknown handles, handles of another settlement account and handles of another payer or payee are answered with the same 404, so a merchant cannot discover that a handle exists outside its own scope. The payer must be named with exactly one of payerId or merchantPayerReference; a payout card binding is named by merchantPayeeReference alone and cannot be paid out by once deleted.