def __delattr__(self, item: str):
        """delete the item in dataelement.

        Args:
            item (str): The key to delete.
        """
        if item in ('_metainfo_fields', '_data_fields'):
            raise AttributeError(f'{item} has been used as a '
                                 'private attribute, which is immutable. ')

        if item in self._metainfo_fields:
            super().__delattr__(item)
        else:
            for level in self.levels():
                level.__delattr__(item)
            self._data_fields.remove(item)
delete the item in dataelement.

        Args:
            item (str): The key to delete.
        
mmpose/mmpose/structures/multilevel_pixel_data.py