code: @BetaApi
    public final Operation deleteSignedUrlKeyBackendService(String backendService, String keyName) {
  
      DeleteSignedUrlKeyBackendServiceHttpRequest request =
          DeleteSignedUrlKeyBackendServiceHttpRequest.newBuilder()
              .setBackendService(backendService)
              .setKeyName(keyName)
              .build();
      return deleteSignedUrlKeyBackendService(request);
    }
docs: Deletes a key for validating requests with signed URLs for this backend service.
  
  <p>Sample code:
  
  <pre><code>
  try (BackendServiceClient backendServiceClient = BackendServiceClient.create()) {
  ProjectGlobalBackendServiceName backendService = ProjectGlobalBackendServiceName.of("[PROJECT]", "[BACKEND_SERVICE]");
  String keyName = "";
  Operation response = backendServiceClient.deleteSignedUrlKeyBackendService(backendService.toString(), keyName);
  }
  </code></pre>
  
  @param backendService Name of the BackendService resource to which the Signed URL Key should be
  added. The name should conform to RFC1035.
  @param keyName The name of the Signed URL Key to delete.
  @throws com.google.api.gax.rpc.ApiException if the remote call fails