I used the drill and punch method, it worked well for me.
All of the above are good,it just depends on what technique you prefer, and what physique you have.
I used the brute force and ignorance approach.
I drilled the heads after grinding a flat on the surface(as Alvin)mentioned and progressively went up in drill size 'till I matched the rivet shank size,the rivet head literally fell off,then pounded them out with a flat punch.
Try to use a punch as near the rivet size as possible to avoid 'mushrooming' the rivet shank.
