I bought "conversion kits" which supposedly do the job in 5 minutes, but the I discovered that the kit is designed for the current type of can, and is not suitable for the ones that are up there (22 years old). So I decided to remove the cans completely and patch the drywall. After removing the can there is still a mounting bracket up there, which seems to be firmly stapled to the adjacent 2x4, and looks as if it is too wide to go through the 6-inch hole. Do I have to cut a much larger hole to get it out, or is there a secret way to collapse the bracket in some way? I cannot access these from above.
As long as you disconnect the wiring to them, nothing says that they can't just stay in the ceiling. I'd try reaching through the hole with a flatbar to detach them from the framing, disconnect any wiring, and then just push them out of the way.
I'd widen the hole as big as you need to get the job done right, remove the cans, and patch the drywall when you're done. Alternatively, you can hide the hole (or a sloppy drywall patch) with a ceiling medallion and mount your pendents to that.