Remove the “Default sorting” dropdown

<?php

add_action(
	'wp',
	static function () {
		// Above and below the products, at whatever priority the theme uses (Storefront moves it).
		foreach ( array( 'woocommerce_before_shop_loop', 'woocommerce_after_shop_loop' ) as $hook ) {
			$priority = has_action( $hook, 'woocommerce_catalog_ordering' );
			if ( false !== $priority ) {
				remove_action( $hook, 'woocommerce_catalog_ordering', $priority );
			}
		}
	}
);