/**
 * Disable SKUs completely
 */

add_filter('wc_product_sku_enabled', '__return_false');


/**
 * Hide SKUs in the frontend but keep them in the backend
 */

add_filter('wc_product_sku_enabled', 'cc_hide_frontend_skus');

function cc_hide_frontend_skus($enabled){

  if(!is_admin() && is_product()){
    return false;
  }

  return $enabled;

}