Set Free Delivery Fee on Order above a specific amount on WooFood 3
The below article is for WooFood , Food Ordering Plugin for WordPress and WooCommerce. If you don't already have it . Please take a look on the product page
add_action('woofood_delivery_fee_filter', 'wpslash_change_delivery_fee_based_on_order_value', 10, 1);

function wpslash_change_delivery_fee_based_on_order_value($default_delivery_fee)
global $woocommerce;
	$subtotal = WC()->cart->subtotal;
	if($subtotal > 25)
		return 0;

	return $default_delivery_fee;
The above article is for WooFood Food Delivery Plugin for WooCommerce