restoring items in shopping cart

If a shopper puts items in their shopping cart but does not actually buy, I DO NOT want
the shopping cart saved and items restored when they log back into their account.  How do I stop
this from happening?  thanks.

to stop this.

/library/cart/customer.php

remove this

if ($customer_info['cart']) {
$this->cart->restore(unserialize($customer_info['cart']));
}

that should not keep the customer with a clean cart

worked great !!  thanks so much for quick response.