code: func (s *ReactionsService) DeleteReaction(ctx context.Context, id int64) (*Response, error) {
  	u := fmt.Sprintf("reactions/%v", id)
  
  	req, err := s.client.NewRequest("DELETE", u, nil)
  	if err != nil {
  		return nil, err
  	}
  
  	// TODO: remove custom Accept header when this API fully launches.
  	req.Header.Set("Accept", mediaTypeReactionsPreview)
  
  	return s.client.Do(ctx, req, nil)
  }
docs: // DeleteReaction deletes a reaction.
  //
  // GitHub API docs: https://developer.github.com/v3/reaction/reactions/#delete-a-reaction-archive