Hi Benny - you will need to go into the actual purchase order and RMB on the header and select “view change order” or similar (you may be able to do this direct from the line in your overview screen shown in your post too but I don’t remember).
 

You’ll then need to either cancel the line on the change order and update the PO from that screen to cancel the line on the PO.

Hope this helps

Dave

Hi Dave

Thank you , -it worked perfectly

Have a nice day

Benny