/**
 * Disable default drupal search.
 */
function yourmodule_updates_update_7001() {
  // Disable default drupal search.
  variable_set('search_cron_limit', 0);
  // Delete unused search data.
  db_delete('search_dataset')->execute();
  db_delete('search_index')->execute();
  db_delete('search_node_links')->execute();
  db_delete('search_total')->execute();
}