const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({reason: '<string>'})
};

fetch('https://api.keystoneos.xyz/v1/admin/settlements/{settlement_id}/rollback', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

{
  "settlement_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "previous_state": "<string>",
  "current_state": "<string>",
  "action": "<string>"
}