can I delete a pay run that has been finalised but not lodged with the ATO?

Since the pay run hasn’t been lodged with the ATO yet, I recommend unlocking it rather than deleting it. This'll let you correct the payroll details and recalculate the pay run before you submit it.

A finalised pay run can be unlocked and edited if no automated super payments have been made. Deleting it is also an option if you need to start over, but take note that this action can't be undone and any related data will be unrecoverable. Here's how: 

1. Navigate to All apps, then Payroll, and select Employees.
2. Go to the Pay Runs tab, then select the Pay Run you wish to unlock. 
3. Click the Pay Run Actions dropdown, then Unlock.
4. Enter a Comment about why you’re unlocking the Pay Run, then Unlock it.

Once done, update the incorrect details and recalculate the pay run. After everything looks right, finalise the pay run again, and you'll be set to lodge it with the ATO.

Please don't hesitate to reply below if you have further questions. I'll respond promptly.