In Russia they sometimes publish some things in blogs that might be considered unethical to publish in some places. For examples this is a guide for removal a magnetic security tag you can meet in dress stores. Person who published this says it's just for fun, or for using in actual store or just to use if you got the item and they forgot to remove the tag in the store so you can do it by yourself. It's kind of his disclaimer.
So if to get back to the guide all one would need is
...is a very strong magnet. "In everyday life the most strong magnet you can get is the magnet from the computer's Hard Drive. You can usually get one non-working disk from some computer store who sells used hardware. It would cost you dollar or two", says the author.
"The magnet itself is glued to the surface - you need to insert the blade between the magnet and the disk and then you have a magnet!"
"One magnet might be not enough, you gotta get a few of such for best results. But beware - anything magnetically-sensitive like credit card or small electronic devices should be taken away from it - or it can be easily harmed"
"So when you have the magnets put them one to another (you can see on the picture)"