There is a lip on my brake pad from bad positioning. Can I remove the lip? One of my bikes had the brake pads positioned poorly and they developed a pretty pronounced lip where the pad hung off machined braking surface on one side. The bike is using cantilever brakes.

These brakes have great stopping power, but It's hard to adjust the pads since one of them has an uneven surface due to the protruding lip.  Is there any way to cut off, grind off, sand off, or otherwise remove the extra material from the brake pad to make it even again?
You can trim off the lip with a sharp blade, if you do it carefully. However, I normally recommend that the lip be filed off with the flat side of a 3/4" bastard file. 

It's more accurate, the mechanic is less like to hurt the self if they slip, and it has the added benefit of roughing the surface of the pad to remove any heat glazing at the same time you are flattening the surface of the pad.