Removes subdirectory within checkpoint_folder
        Parameters
        ----------
            checkpoint_dir : path to checkpoint

def delete_checkpoint(self, checkpoint_dir):
        """Removes subdirectory within checkpoint_folder
        Parameters
        ----------
            checkpoint_dir : path to checkpoint
        """
        if os.path.isfile(checkpoint_dir):
            shutil.rmtree(os.path.dirname(checkpoint_dir))
        else:
            shutil.rmtree(checkpoint_dir)