Clear the #woocommerce #cart with a query string parameter

functions.php

<?php

/*
 * If you add ?clear-cart to the URL the cart will be emptied
 */
add_action( 'init', 'woocommerce_clear_cart_url' );
function woocommerce_clear_cart_url() {
	if ( isset( $_GET['clear-cart'] ) ) {
		global $woocommerce;
		$woocommerce->cart->empty_cart();
	}
}