'Internal; deletes a single asset\'s metadata.
Arguments:
asset_key (AssetKey): key containing original asset filename
Returns:
Number of asset metadata entries deleted (0 or 1)'

@contract(asset_key='AssetKey')
def delete_asset_metadata(self, asset_key, user_id):

    def _internal_method(all_asset_info, asset_idx):
        '\n                                                Remove    the    item    if    it    was    found\n                                                '
        if (asset_idx is None):
            raise ItemNotFoundError(asset_key)
        all_asset_info.pop(asset_idx)
        return all_asset_info
    try:
        self._update_course_assets(user_id, asset_key, _internal_method)
        return 1
    except ItemNotFoundError:
        return 0
