I believe there are little prongs that stick out the side of the drawer. They catch on the slide when fully extended. You just open the drawer till the prong hits the slide, then close the drawer just enough to be able to pry the prong in. A small screwdriver should do the job. You can push th eprong back out before you re install the drawer.
There are also a type of clip on some Craftsman drawers, those will be obvious if you have them. You just pry them up from the rear, and pull them forward. They kind of look like a thick hair pin. I don't think you have them, but you might.