using RestSharp;


var options = new RestClientOptions("https://api.mattildapayments.com/vault-forward/configs/{config_id}/authentications/{authentication_id}");
var client = new RestClient(options);
var request = new RestRequest("");
request.AddHeader("Authorization", "Bearer <token>");
var response = await client.DeleteAsync(request);

Console.WriteLine("{0}", response.Content);

{
  "type": "error",
  "code": "unauthorized",
  "status": 401,
  "message": "No valid API authentication found",
  "details": []
}