If you generate your invoices within Music Monitor, see instead Reverse a Billing Run - Invoices.
Overview
Part of the process of finalising a list of accounts lines is to mark them with a Date Billed. That causes Music Monitor to lock them against later edits, and also prevents them from being picked up in the next billing run and billed again.
So to reverse the billing run, you just need to remove the entry from the Date Billed field. This does not remove the line items, it just removes the entries in this field.
Caution
Once accounts lines are finalised, the resulting export is used in your other business systems, so changing the lines in Music Monitor can lead to discrepancies between the records in your different systems.
Therefore, Music Monitor settings do not allow these lines to be edited once they are finalised.
If you have already sent the exported file off for use in another system, and later discover an error, so you need to reverse a billing run, everyone who has received the earlier data needs to know as well.
That's why Music Monitor only allows these records to be edited using the "admin" privilege set, which you should use only on these occasions where special privileges are needed to fix an error.
So to start this process, you must log out of Music Monitor, and log back with an an admin account.
Which Lines to Reverse
If you need to reverse a billing process, it is generally because you have made an error in the billing run and need to undo the whole batch. So the way to identify which lines are affected is usually by the Date Billed.
Even if not all of the lines in the billing run are wrong, the simplest and safest option in many cases is to reverse the whole billing run and re-do it correctly.
If that is not your situation, and you need to reverse a billing run for some other reason, consider carefully how to bring in just the set of line items you need. Contact our support team if needed.
Reverse the Process
Select the Date Billed entry in one of the records and delete what is entered.
While the cursor is still in that field, go to the grey top bar and select Records > Replace Field Contents.
You will see a dialogue that asks you to confirm that you wish to replace the content of that field in all the records you have in your found set. Check that it is proposing to replace the right fields with the right (blank) entry, then select Replace.
Those accounts lines no longer have a billing date, and so are listed as unbilled and will appear in your list next time you run the Process All Unbilled Amounts script.