Removes all of the index status triples from the datastore

        Args:
        -----
            rdf_class: The class of items to remove the status from

def delete_idx_status(self, rdf_class):
        """
        Removes all of the index status triples from the datastore

        Args:
        -----
            rdf_class: The class of items to remove the status from
        """

        sparql_template = """
            DELETE
            {{
                ?s kds:esIndexTime ?esTime .
                ?s kds:esIndexError ?esError .
            }}
            WHERE
            {{

                VALUES ?rdftypes {{\n\t\t{} }} .
                ?s a ?rdftypes .
                OPTIONAL {{
                    ?s kds:esIndexTime ?esTime
                }}
                OPTIONAL {{
                    ?s kds:esIndexError ?esError
                }}
                FILTER(bound(?esTime)||bound(?esError))
            }}
            """
        rdf_types = [rdf_class.uri] + [item.uri
                                       for item in rdf_class.subclasses]
        sparql = sparql_template.format("\n\t\t".join(rdf_types))
        log.warn("Deleting index status for %s", rdf_class.uri)
        return self.tstore_conn.update_query(sparql)