Remove posts_orderby filter then add it back in

To add back the filters that were removed you’d have to know what was hooked in originally in the first place. You could crawl the global $wp_filter array, but this should do the same at far less effort:

function remove_query_order($order) {
  remove_filter('posts_orderby','remove_query_order',PHP_INT_MAX);
  return '';
}
add_filter('posts_orderby','remove_query_order',PHP_INT_MAX);

Add the filter before the query you want it to effect and it will remove itself.