Remove related products in Vantage Theme

To remove the Related Products block you’ll need to create a child theme, add a functions.php file to that child theme and enter the following into that file:

I did the above and now where do I enter the file?
<?php
function woocommerce_remove_related_products(){
remove_action( 'woocommerce_after_single_product_summary', 'woocommerce_output_related_products', 20);
}
add_action('woocommerce_after_single_product_summary', 'woocommerce_remove_related_products');

Thank you