Unable to delete unwanted shopping carts

Dear All,

We are running SRM5.0 and we have a problem deleting unwanted shopping carts. We have shopping carts that we created Purchase Orders for. It was then decided that the requirements is no longerr required so we deleleted the PO at header level (the line items show that they have been deleted). When we tried to delete the shopping cart, the delete buttons on the shopping cart in 'Monitor Shopping Carts' are greyed out and so we cannot delete the shopping cart. How can we delete these shopping carts as the carry on appearing on our Sourcing Cockpit?

Thank you.

Pedzi