Requests closure. Closing is asynchronous: a 202 Accepted returns the record with status: CLOSING, and the account reaches CLOSED once the banking partner acknowledges. Poll GET /virtual_accounts/{id} for the transition. Calling it again while a close is in flight, or after it completes, returns 200 OK. Accounts in PENDING, BLOCKED or FAILED cannot be closed and return 409 Conflict. An unknown id returns 404 Not Found; an account belonging to another platform returns 403 Forbidden. The request body is empty.