There is a lip on my brake pad from bad positioning. Can I remove the lip?
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.