You can run the Profit and Loss by Class (summary and detail) reports but will display mixed with both active and inactive classes.

The issue here is there's no way to filter the report for inactive/deleted classes only. That's more seems like QBO lacks a way to filter the report for available data. These are known issues in QBO. Hope they focus on improving reporting data.

(In the meantime, you can always export to excel and filter the report as you need until they improve the reporting tool which seems like Neverland.)