'Deletes an existing metadata.'

def delete(self, req, snapshot_id, id):

    context = req.environ['cinder.context']
    (snapshot, metadata) = self._get_snapshot_and_metadata(context, snapshot_id)
    if (id not in metadata):
        raise exception.SnapshotMetadataNotFound(snapshot_id=snapshot_id, metadata_key=id)
    self.volume_api.delete_snapshot_metadata(context, snapshot, id)
    return webob.Response(status_int=http_client.OK)
