Hide shipping rates when free shipping is available

WooCommerce shows by default all the shipping methods for a matching shipping zone. If you want to hide them add this piece of code.

function yabu_hide_shipping_when_free( $rates ) {
    $free = array();
    foreach ( $rates as $rate_id => $rate ) {
        if ( 'free_shipping' === $rate->method_id ) {
            $free[ $rate_id ] = $rate;
            break;
        }
    }
    return ! empty( $free ) ? $free : $rates;
}
add_filter( 'woocommerce_package_rates', 'yabu_hide_shipping_when_free', 10 );