WooCommerce - Hide shipping methods for specific shipping classes / Add support to hide shipping methods for specified shipping classes to WooCommerce

functions.php

<?php

add_filter('woocommerce_package_rates', 'hide_shipping_methods', 10, 2);

/**
 * Hide specific shipping methods for packages with negative cost set.
 * There is no need to hard code any IDs of shipping classes or products if you can just set negative value
 * on the back-end and then delete these methods on the fly.
 *
 * @param $rates
 * @param $package
 * @return mixed
 * @version WooCommerce 3.0+
 */
function hide_shipping_methods($rates, $package) {
   foreach ($package['rates'] as $key => $value) {
       if ((float)$value->cost < 0) {
          unset($rates[$key]);
      }
  }

  return $rates;
}