Demagnetizing CDs is an idea that has been around (and argued about) for decades.
Remember the Bedini Ultra Clarifier?
This device came out in the 1990s and was essentially a motor that spun a CD at a high rate of speed over a number of magnets with the goal of dispersing and magnetic charges that had built up on the disc.
Like most tweaks in this hobby that Ultra Clarifier stirred up all kinds of sh#t storms. in a 1994 review, Myles Astor wrote about it "The Bedini Ultra Clarifier sets a new benchmark for degree of sound improvement. You owe it to yourself to get this product if you listen to digital. Otherwise, you haven't heard your discs." And on the other side of the fence were all kinds of nay sayers making they typical comments like is is snake oil, witchcraft or using it would make your penis fall off. (OK, I made the last one up, but you get the idea. )
Like everything else in this hobby the only thing that really matters in the end is how it sounds to
your ears in
your system. If you like, you buy it, if not you move on and invest your money elsewhere in your system. and the hell with that anybody else thinks...... or measures.
I got a used one for not a lot of money and used it regularly for quite a while, but then when we moved I did not have a place to put it where it was out and easily accessible. So it sits in a cabinet behind a closed door and out of sight, out of mind, I just have not used it in quite a while. Now I am going to have to pull it out and play with it again.
Of course I just finished ripping about 1600 CDs so they can be played through Roon. I probably should have demagged them first.