add_filter('template_include', 'remove_orderby_for_auctions', 99);

function remove_orderby_for_auctions($template){
	if (get_query_var('is_auction_archive', false)) {
  		remove_action( 'woocommerce_before_shop_loop', 'woocommerce_catalog_ordering' ), 10 );
  	}	
	return $template;
}