Options for Cancelling PO Line

We have two lines on a purchase order that are hopeless and need to be cancelled.  Unfortunately, when we click on CANCEL from the detail line, we get the error "Item Number Invalid".  This is incorrect, the item number is in the Item Master and Item Branch. 

Are there any options for deleting these two lines, other than via SQL?

If SQL is the only option, which fields should be updated?

Thank you.