Purchase order and Purchase requisition link can be removed after po confirmation

Hi all

We have one scenario in production where po was created for all items defined on PR. Po got confirmed and later user delete few lines from po.now even after deletion of po lines those items are showing that same po number in pr lines-)details and pr status is also closed.this pr is not visible on released approved pr screen.so i even can’t create new po.

1. How can we remove the link for this po from pr lines..

2. If it is not able to remove /correct the existing pr then what is the alternative.

Do we have to cancel both pr and po and need to create new one.

Please advise.

Thanks

Shri