Does "non-functioning" mean it won't grind, or just that the water won't go down? If it won't grind, use the hex wrench and insert from underneath to loosen. If it's humming but not turning, see if there is a reset button underneath and push it.

Easiest would be to get it working again, then use a strainer into the drain.

Second easiest, if the water is just not draining, would be to clear it. Buy a snake, loosen and remove the trap, and insert, feed it, turn, etc. (You may need a 12" adjustable, channellock type wrench to turn the nuts for the trap). It will likely be smelly and messy, so remove everything from the cabinet. Not a bad idea to temporarily lay some newspaper in there, too.

Now, if you still want permanent removal, at a minimum that means turning off the power, dropping the disposer, lay it on it's side (watch for leftover water), disconnecting the wire (or just clip it with wire cutters close the unit), cap any exposed ends of the wire (or wrap a "clipped" end with a bunch of electical tape), and roll it up and tuck it way back into the cabinet. Then install a basket, slip-nut type 1 1/2" drain, etc. You will need plumber's putty, a hacksaw (to cut some of the pipes) and that 12" wrench. Maybe a "tailpiece" extension, too.

Also, when you remove the disposer flange from the sink, you'll want to wipe off the old putty. Be careful! That sink hole edge can be extremely sharp and cut like a razor.

You can probably find some youtube videos to walk you through the install.

One other thing. You may need the proper "trap adaptor" to connect the drain to your existing pipe. Make a note of what kind of pipe you have (PVC? cast iron? etc.) Tell the folks at the store what you think you have and they'll find you a connector ot two (you can always return the extra stuff.) Good luck.