There probably isn't a universal solution because different manufacturers attach the labels in different ways and with different adhesives. If you are dealing with very old cans, there may be additional differences.
I would start with steam. There's a good chance that it will release the glue holding the label to itself in a loop. Unfortunately, steam will also soften the paper, so it will likely tear if you try to pull on it. Just keep applying steam at the seam until the paper separates on its own.
Assuming the label is also glued to the can, the steam will likely also release that. It will penetrate paper and it will warm the can, both of which will help, but the fastest release will happen if you can direct the steam into the seam between the label and can. As the paper releases, let gravity pull the paper away, exposing more seam as you work your way around the can.
If the paper is glued to the can only at the seam where it is glued to itself, and if you can sacrifice the seam, you could just use a hobby knife to cut the label off on both sides of the seam.