我有两种配送方式，我想禁用默认的固定费率配送方式。我试过这种方法here 但它不起作用

add_filter( \'woocommerce_package_rates\', \'hide_shipping_method_based_on_shipping_class\', 10, 2 );
function hide_shipping_method_based_on_shipping_class( $rates, $package )
{
    if ( is_admin() && ! defined( \'DOING_AJAX\' ) )
        return;

    // HERE define your shipping class to find
    $class = 92;

    // HERE define the shipping method to hide
    $method_key_id = \'flat_rate:7\';

    // Checking in cart items
    foreach( $package[\'contents\'] as $item ){
        // If we find the shipping class
        if( $item[\'data\']->get_shipping_class_id() == $class ){
            unset($rates[$method_key_id]); // Remove the targeted method
            break; // Stop the loop
        }
    }
    return $rates;
}