WooCommerce 3.3 - Hide uncategorized category from the shop page on the frontend

functions.php

<?php // Do not include this if already open!

/**
 * Code goes in theme functions.php.
 */
add_filter( 'woocommerce_product_subcategories_args', 'custom_woocommerce_product_subcategories_args' );

function custom_woocommerce_product_subcategories_args( $args ) {
  $args['exclude'] = get_option( 'default_product_cat' );
  return $args;
}