How to dismantle an Atomic Bomb
One of the cool tricks you can do with a core is to dope it with heavy water so that you end up with more fast neutrons. Actually the thing to really worry about here is the fast neutrons , they are bad news.
Be safe. Ok. Take the trigger offline - usually there is a keypad, the detonation sequence is likely heavily coded so that it can't be triggered by mistake but you just want to take it apart so things will be in your favor. This thing will not likely detonate by default if the trigger is breached. I said likely. Depends on whose bomb.
Take out the triggering mechanism that would've driven that little pellet core into the main fissible material. Once you can get past the keypad, its probably just screwed into place in the center behind the pad.
Your main problem won't be the bomb itself but the security around the trigger mechanism - there is a good probability it will have a satellite/gps transceiver on a protected circuit so remember, before you start, get yourself inside a metal box. It will block the signal. Electromagnetic field cannot go through a sealed metal box.
The two parts, taken apart will be safe enough .. but commonly the trigger mechanism is protected by a secondary device, much in the same way as cash in a vault often has an exploding paint mechanism to blow up in your car when you drive away. So be careful of that too when you take it out. Also remember, as soon as you screw with it , it will start talking.
Once you have the trigger and core separated you can dispose of the core quickly. Its bad for flowers, children and living things. Don't get any on you or breathe in any dust. If it gets in you it will kill you. Get some dishwashing detergent or other soap and put it in that, so that no dust or particles can fly off it. It will likely be round since that is the easiest shape to make the thing work.
The trigger is another story. By the time you've read this and followed instructions its likely the trigger has communicated to whatever intelligence agency is responsible for monitoring the location of the bomb, your lat/long or, cords, for short.
So the easiest way to dismantle an atomic bomb is to damage the trigger enough to bring them running and then split. And I mean, get out of there fast. You know, like that adage about Lynn, Massachusetts? Lynn, lynn city of sin. Never go out the way you came in. Once they find what you left for them, they'll take it apart for you. And recycle it.