By default, WooCommerce displays all shipping options on the cart and checkout pages. If you want to show only the free shipping option on these pages, add the following code to functions.php:
/**
* Hide shipping rates when free shipping is available.
* Updated to support WooCommerce 2.6 Shipping Zones.
*
* @param array $rates Array of rates found for the package.
* @return array
* @link https://docs.woocommerce.com/document/hide-other-shipping-methods-when-free-shipping-is-available/
*/
function prefix_hide_shipping_when_free_is_available( $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', 'prefix_hide_shipping_when_free_is_available', 100 );