curl --request DELETE \
  --url https://app.sendmux.ai/api/v1/mailboxes/{public_id}/keys/{key_id} \
  --header 'Authorization: Bearer <token>'

{
  "ok": true,
  "data": {
    "deleted": true,
    "id": "<string>"
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}