You can process a leaver in advance payroll by clicking the Terminate Employee option. I'll show you how:
Choose the employee name within the pay run.
Under Actions, select Terminate Employee.
Enter the Termination Date and then Save.
It's a good thing that you record the employee as a leaver before running their final payroll. This way, HMRC will be notified of the leaver in the FPS and a P45 will be generated within QuickBooks. Also, make sure that the date should fall within the pay period of the next pay run.
In case you need to rollback a payroll, you can follow the steps below:
Go to Pay Runs.
Select the pay-period listed.
Click Pay Run Actions.
Tap Unlock then Delete.
You can now be able to re-run the payroll, just click the New Pay Run button on the dashboard page.
I'm adding this article in case you got other questions with QBOAP: QuickBooks Online Advanced Payroll Hub. This is a page with a collection of links for articles related to QBOAP, from Getting Started to Processing Pay Runs.
You can get back to me if you have any other questions about QuickBooks. I'm here to help. Take good care.