If you need to disconnect the CO from the WO, it can be done. You can try out the following, but results depends on the state of the Customer Order. First need to get the CO to Planned state from the current state. Then from the work order side you can undo the transfer of CO lines and then the CO will be set  to Cancelled state. This is what I think and based on your actual situation, extra steps might required. Hope this helps.

Thank you for your response. Unfortunately we are unable to return the customer order to the planned status.