Clear Cart session after log out

Hi all,
I have to account in my opencart site. I found one bugs here. When i login by one account and add some products in the cart. But i didn't complete the transaction. Then when i login my another account i found the car is already added the previous products. How can i clear the cart session when i logout. I need to clear the cart for every logout, because customer role is different.

i tried by updating controller account/logout.php [ $this->cart->clear(); ], but have no changes.
Thanks

Saiful Islam

This works fine on my site. Perhaps it is something on your localhost setup?
I have 2 accounts
I can login with Customer A and add "Ipod" to my cart.
Logout and login with Customer B. There is no iPod in customer B's cart.