Taking it down piece by piece is something you don't want to do unless you have done it. It is a method of jackig it up, taking a ring off all the way around, setting it down, and repeating the process.
However if you want it DOWN; cut a 10" hole or so in one side as low as you can, 90 degrees each direction of that hole (say 10' up from the ground) cut another about the same size. Now the section of bin opposite the first hole you cut wrap a chain around that through your second and third holes, run a chain through your first hole to a tractor (I will add a LONG section of chain to your tractor) and pull. I would think anything above 50 hp (2wd or 4wd) should pull it down, if not get a bigger tractor on it. A full size truck with a big winch would work, a tow truck should be able to get the job done.
Once it is down on it's side it will be alot easier to work with seeing that you can then take it apart ring by ring without specialized equipment. The metal on bins is thicker than what you would first think, a torch would work well however you are dealing with galvanized steel and burning the zinc off can be hazardous to your health. A cut off saw with a steel cut wheel would work very well, lots of sparks though and it will be extremely loud. A sawzall would work but you're gonna go through alot of blades, circular saw with a metal cut abrasive blade, sheetmetal nibblers would work.
I wouldn't advise pushing it over with your front end loader, they have a tendency to buckle and fall rather than push over, their strength relies on their rigid round structure, take one side out they tend to go over the direction they are weakest.
