It's been a while, but here goes, IIRC. Take the stocks off and you will see the back side of the spring pushing on the two magazine release pieces, one coming from the left and one coming from the right. Take a screwdriver or something and push the spring towards the front of the gun while tipping it back and forth. You'll probably have to push the spring in pretty hard. I can't remember which side is supposed to come out first, but one side should drop out when you get the spring tension off, then the other side should fall out. You may have to shake the pieces out while pushing the spring. It is kind of a pain in the ass and it would be good to have 3 hands, but once you get the hang of it, it's not too hard. IMHO, it is one of the better designs for an ambi mag release and works well but is a PITA to take apart.
Bub75