/**
 * Check the cart for specific shipping classes, remove Free Shipping if they are present
 *
 * This code will remove free shipping if a product is in the cart that can not be delivered for free
 * Assign a shipping class to those products and add the slug to the $freeshipping_array
 * Multiple shipping classes can be added to the array
 *
 * Add the code to your theme functions.php file
 */
add_filter( 'woocommerce_package_rates', 'unset_free_shipping_when_product_in_cart' , 10, 1 );
function unset_free_shipping_when_product_in_cart( $available_methods ) {
	
	/**
	 * Set free shipping variable to true
	 * 
	 * Free shipping is allowed unless we find a product with a shipping class that 
	 * does not allow free shipping
	 */
	$freeshipping = true;
	
	// Setup an array or shipping classes that do not allow free shipping
	$freeshipping_array = array( 'local-delivery' );
	
	// loop through the cart checking the shipping classes
	foreach ( WC()->cart->get_cart() as $cart_item_key => $values ) {

		$shipping_class = get_the_terms( $values['product_id'], 'product_shipping_class' );

		if( in_array( $shipping_class[0]->slug, $freeshipping_array ) && $freeshipping ) {
			$freeshipping = false;
			break;
		}
	}

	// Unset Free Shipping if necessary
	if( $freeshipping == false ) {
		unset( $available_methods['free_shipping'] );
	}
	
	return $available_methods;
}