There are many reasons to not include related products on your single product page. Regardless of those reasons, there’s a solution for you if you’re looking to remove, or stop, the related products from showing on your single product page.
This single line of code should be enough to disable the related products from showing up. In fact, this line actually simply removes the related products ‘action’ from being run on the page all together.
Add this code in your theme’s functions.php file of your active child theme (or theme).
remove_action( 'woocommerce_after_single_product_summary', 'woocommerce_output_related_products', 20 );