Taco, the baseplate of the KRD mags just slides right off; but not easily. You can try holding the mag against a flat surface and pushing down on it at an angle to get the baseplate sliding forward a bit; but I didn't have much luck with that.
What worked for me was just applying pressure to the back of the baseplate with both thumbs to 'walk' the baseplate off. I'd push on one side until I saw a tiny bit of movement and then push on the other side until they were even. I eventually got the baseplate off with some work. After the first time, it goes on andoff much easier.