Clearing AR Invoices

I need to clear multiple AR Invoices for loans.  Payments against loan balances years ago changed to be offset by a GL account as loan software was utilized to track loan balances.  At this point the loans are paid off and the invoices are sitting in the AR Customer profiles.  When I run an AR trial balances the invoices show up with significant balances.  How do I clear the loan invoices for the loans that are paid off?