A/R invoice reversal

SUGGESTED

A number of invoices were added in may however some of the may invoice dates were dated Jan so it ended up in Jan. The invoices were reversed in the general ledger since there were already posted. 
when the ages trial balance was run for the customers the invoices were still there. How can they be removed from the aged trail balance. Should I do a credit note for each invoice so as to remove the invoice? Urgent question please