Remove corrected invoice from a credit memo

Hi

I have a line on invoice that need to be discarded. However, this line cannot be discarded as it it being referenced by an active correction.

So, I would discard the referenced correction on a credit memo line. However, when I attempt to discard the line on the credit memo I receive the following message.

"This invoice is a quick credit, it can be cancelled at header level but you cannot discard individual line."

So, I check at invoice header and it is marked as a quick credit. I can't cancel this credit memo as there is another line with matched with a PO. (the line I would line to discard was not mached to PO)