Remove WooCommerce hierarchical product category URL rewrites

wc_remove_cat_hierarchy.php

<?php

# the neat way using WooCommerce filter

function remove_wc_product_cat_hierarchy($args){
    $args['rewrite']['hierarchical'] = false;
    return $args;
}
add_filter('woocommerce_taxonomy_args_product_cat', 'remove_wc_product_cat_hierarchy');

# this is the wrong way cause it throws 404 and adds another override

function remove_wc_product_cat_hierarchy() {
    $product_cat_args = get_taxonomy( 'product_cat' );
    $product_cat_args->rewrite['hierarchical'] = false;
    register_taxonomy( 'product-category', 'product', (array) $product_cat_args );
}
add_action( 'init', 'remove_wc_product_cat_hierarchy', 11 );

?>