code: func (s *PresenceService) DeleteNamespace(namespace string) error {
  	if namespace == "" {
  		return trace.BadParameter("missing namespace name")
  	}
  	err := s.Delete(context.TODO(), backend.Key(namespacesPrefix, namespace, paramsPrefix))
  	if err != nil {
  		if trace.IsNotFound(err) {
  			return trace.NotFound("namespace %q is not found", namespace)
  		}
  	}
  	return trace.Wrap(err)
  }
docs: // DeleteNamespace deletes a namespace with all the keys from the backend