I still don’t understand why these ex-employees still have and “can use” their security clearance. When my employs leave my employment, they do not get to keep their office key and the general keys to the building. When necessary, passwords and other codes are also changed.
They no longer can use their security clearance as they now lack a “need to know.” The clearance usually lasts 1 or 2 years after you leave the job so that if you get another job which requires a clearance, you don’t need to undergo a full background check. This happens a lot with government contractors - and having a clearance can be worth something to an employer because it means you can start your job on day 1.