How do you disassemble a jennings nine 9mm?
Throw it away. ok. I'll be nice.
On the back of the slide, where you see the firing pin when you cock the pistol. There is a plastic piece or "button". Ensure the gun is not cocked and empty and then take a pen and push that plastic piece in while gently lifting the rear of the slide when the "button" is pushed all the way in. Slide should just lift off.
You may have to pull back a little on the slide to get it to lift up, but just a little. Less than an eighth of an inch. Once the slide comes up far enough to clear the barrel, it will move forward and off. The barrel does not come off the frame, it's pinned in place. The only other part to normally come out in a field strip is the recoil spring, which encircles the barrel. You'll end up with three peices.
Once you're done, throw it away (for real this time).