Disconnect the wiring, easy unless hardwired into the wall. You will have to do this either way. Disconnect the drain plumbing. It is going to be hard to describe mounting method. The disposal is connected to the sink drain. There is a giant "washer" that has three "circles" built into the outer lip of the washer. You must turn it counterclockwise to remove the disposal. The disposal is not that heavy. I would leave it connected and just disconnect the wiring and plumbing. If you are strong enough to lift both. Reattaching the disposal can be a challenge.

I would do it a bit differently. Leave it wired, but either shut off the circuit or just put a piece of tape over the switch to keep hands off. As for dropping it down, first disconnect the GD's connection to the drain. Then HOLD the GD from underneath while you rotate the retaining ring mentioned above. (Easy way to rotate the ring is by sticking a screwdriver sideways into one of the round horizontal holes to help lever it conterclockwise.) CAUTION: Again, make sure you HOLD the disposer when you turn the ring because it will release/fall at one point. Then just lay it down in the cabinet (there may be some water left in it to clean up).

Putting it back is better done with two people for a novice. Lift the GD back in place up against the sink bottom connection, and then try your best to get that retaining ring to catch the edges on all three sides (it can be a pain). Then lever it with screwdriver or hammer to tighten fully. (Keep in mind you may have to orient the GD's drain tube with the existing plumbing by rotating the GD a bit before you tighten the retaining ring fully.) Good luck.