How to Terminate employee after a payroll has been run?

Hi there,After the Weekly payroll has been run for a period, it has been identified that few of the employees need to be terminated on a prior date. The payroll and all of the post processes (NACHA & transfer to GL) have been run on them. 

We cannot now enter the past 'actual termination date' as there is a future payroll run on them. Can some one please help me with the options that we have to handle this scenario? 

Thanks,

Sashi.