Click on the Bill Batches Tab which can be found in the Accounting Center section of the Invoicing Screen. Find the bill batch record you would like to undo. If you have created any invoices from the bill batch record, you will not be able to undo it. Click the Undo Billing link in the Commands column. You will see the bill batch remove itself from the Bill Batches Tab. Additionally, the items that were associated with the bill batch will now appear in the Unbilled Items area at the top of the Invoicing Screen.