code: func (s *IssuesService) DeleteLabel(ctx context.Context, owner string, repo string, name string) (*Response, error) {
  	u := fmt.Sprintf("repos/%v/%v/labels/%v", owner, repo, name)
  	req, err := s.client.NewRequest("DELETE", u, nil)
  	if err != nil {
  		return nil, err
  	}
  	return s.client.Do(ctx, req, nil)
  }
docs: // DeleteLabel deletes a label.
  //
  // GitHub API docs: https://developer.github.com/v3/issues/labels/#delete-a-label