WooCommerce - Do not show images for subcategories

<?php
  // WooCommerce - Do not show images for subcategories
  // code goes in functions.php for your child theme
  remove_action( 'woocommerce_before_subcategory_title', 'woocommerce_subcategory_thumbnail', 10 );
  add_action( 'woocommerce_before_subcategory_title', 'custom_subcategory_thumbnail', 10 );
  function custom_subcategory_thumbnail( $category ) {
    if ( $category->parent == '0' ) {
      woocommerce_subcategory_thumbnail( $category );
    } else {
      // do not show a category image
    }
  }