const options = {method: 'DELETE'};

fetch('http://localhost:4010/v1/atlas/organizations/:id/projects/:projectId/members/:userId', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

{
  "success": false,
  "error": {
    "code": "<string>",
    "message": "<string>",
    "details": {}
  },
  "meta": {
    "requestId": "<string>",
    "timestamp": "<string>"
  }
}