Auspicious first post and first reply. Can't agree that the response was indicative of arrogance and ego.
The charged particles your supposing are not magnetic and I can't recall any platter in the last 40 years being magnetic either. Magnetism isn't your problem. A demagnetizer isn't your answer. But supposing it was, a tape head demagnetiser would be a tedious solution, and the analogy of a toothbrush used to clean a floor actually isn't a bad one at all. A bulk tape eraser would be the way to go if you actually had he problem you supposed which you don't.
The charged particles your supposing are not magnetic and I can't recall any platter in the last 40 years being magnetic either. Magnetism isn't your problem. A demagnetizer isn't your answer. But supposing it was, a tape head demagnetiser would be a tedious solution, and the analogy of a toothbrush used to clean a floor actually isn't a bad one at all. A bulk tape eraser would be the way to go if you actually had he problem you supposed which you don't.