"However, now my end of month balance sheet shows that balance in Accounts Receivables, which it should not.  Now what?"

Did you delete the JE and create a Credit Memo for the open AR balance?

Someone made a JE to take this AR to 0.

When you deleted the JE, the customer should have then had a balance, again.

Then, you create the Credit Memo and Apply it. That puts the customer to 0, again.

Done.