Disabling the product reviews for one product
When editing a product, go for the Advanced tab and uncheck the review options.
Disable the reviews on all products as once
There’s plugin for that (free): https://wordpress.org/plugins/disable-woocommerce-reviews/
This plugin will disable WooCommerce product reviews across your entire shop. There are no settings, simply activate the plugin and you're all set. Deactivate the plugin at any time to re-enable WooCommerce reviews.