I am not clear on exactly what you are doing and how you are doing it.
Are you deleting the AD account or simply removing an AD group from the AD account? Are you making those changes via the IM layer or natively on the AD side?
If you are submitting the changes through the IM layer then you might be able to use PX Policies to trigger on those IM submitted tasks/events to perform additional work.
But if the changes are done natively on the AD side itself and only picked up by running an Explore then those notifications back to IM layer would only be "actionable" via IM Reverse Sync Policies and those would only let you revert the AD change and not take actions on the IM users.
Now if you also had Endpoint Attribute Mappings defined then running the UPDATE of the Explore would update Provisioning Users and so maybe those notifications back to the IM layer would allow for PX policies to be configured on the Provisioning Modify User task to take additional steps but again I am not really too clear on the specifics of what you have, what you are asking, and what you are trying to do.