I inherited a paring knife, shown rightmost in the photo, with an unusually thin, narrow, flexible, 2.5-inch blade. It’s excellent for removing labels from cans before putting them into a recycling dumpster. (I’ve heard that recycling organizations prefer that these labels be removed.) Its flexible tip bends in under the lower edge of the label at a shallower angle than other knives. This, plus its thinness and narrowness, keeps the label’s tear-line from ripping all the way up to the tip while the knife is removing the label. Thus, it is rarely necessary to have to dig the knife in under the label a second time (to restart a rip).
Another advantage is that less force is needed to do the job than what the thicker, wider, stiffer blade of an ordinary paring knife (leftmost in the photo) requires. The latter mostly tears the label with or near its tip, rather than slicing it further down its blade. This extra force means that the blade will sometimes slip and skid along the can, which is irritating and discouraging.
In order to gift my sister with a similar one, I searched online and discovered the inexpensive ($1 each) item shown second from left. It is is superior to an ordinary paring knife, but it isn’t ideal “out of the box,” because its tip is so sharp that it digs into the can, and because its blade widens too suddenly near the tip, tearing the label too soon. So I spent a minute on my bench grinder and rounded over the tip and ground back the surge in the blade, with the result shown in the third photo from the left.
Finally, I put an inch of the blade into a vise and bent it to about a 10-degree angle. This allows it to slide under the label at the start without having to hold the knife at an awkward angle. (You should try to slide the bent tip under the label all the way to the top, at which point it should pop loose, rather than trying to tear the label near the tip.)
You can grind and bend the other three knives similarly, and gift your friends and relatives with them.