How to delete retroactive Notification or at least make sure it does not process

Summary:

We are 3 years into payroll implementation and people have 3 years of payroll history and weekly payroll. Now the issue we are facing is employees are having a stack of old retro sitting around and the person is in deferred status. If we put person in awaiting processing status then old bad retros will get pulled and it will try to pay. we Need a simple solution to delete unwanted retro notifications so that the person can be put back in awaiting processing status.

If we try to delete something in event notifications we get an error that you cannot delete system-generated events. There is a solution floating around to put a date and then run retro so that old retro get marked as completed and there is a significant risk if we have to go back and actually need to trigger something to generate retro like resubmitting old timecards and we need those retros...