code: func (s *APIServer) deleteToken(auth ClientI, w http.ResponseWriter, r *http.Request, p httprouter.Params, version string) (interface{}, error) {
  	token := p.ByName("token")
  	if err := auth.DeleteToken(token); err != nil {
  		return nil, trace.Wrap(err)
  	}
  	return message(fmt.Sprintf("Token %v deleted", token)), nil
  }
docs: // deleteToken deletes (revokes) a token by its value