cannot delete customer with balance

I imported a customer with a balance.  No activity has taken place against that customer.  Now I cannot delete the customer because of the balance that I imported.  I understand that you can't delete a customer when there's been activity against the customer, but in my case there's been no activity - just an uploaded opening balance.  

How can I delete customs with opening balances but no activity? 

Thanks in advance

Mark Stauch