Forget training for label 'label_name'

def forget(self, label_name):
        """
        Forget training for label 'label_name'
        """
        self._bayes.pop(label_name)
        baye_dir = self._get_baye_dir(label_name)
        logger.info("Deleting label training {} : {}".format(
            label_name, baye_dir
        ))
        rm_rf(baye_dir)