Can you delete invoice lines from PO matched invoice that is not validated

Summary:

We have several suppliers that send in PO matched invoices that contain more lines than IDR can consume. Today the invoice technicians are canceling the invoice lines and creating 1 line to match the full amount. But this creates a lot of debits and credits on the approval email that becomes confusing to the approver.

Content (please ensure you mask any confidential information):

We would prefer to delete the lines, but when we attempt to do, we get an error message: This invoice action isn't applicable for the invoice line in its current state. Why can't the lines be deleted? What is the best option?