Here is a quick and easy one-liner to disable the WooCommerce SKU functionality completely.
There are guides on how to hide the SKU from the product page or hide it in the admin, or even hide it with CSS. This snippet is the full works – totally disable the WooCommerce SKU functionality
Add this to your functions.php
// DISABLE WOOCOMMERCE SKU add_filter( 'wc_product_sku_enabled', '__return_false' );