Here's a little trick that works really well for those types of labels. Have you watched professional wrappers at Christmas time curling ribbon with a pair of scissors? It works for removing the backing from the labels as well. Hold the backing of the label against the side of a pair of scissors / knife / even a key with some sharper points on it, and drag it across the edge. This will make the ends separate a little bit, allowing you to take hold and easily separate the pieces.
Check out this site that shows it being done with scissors if you've never seen it
http://www.wikihow.com/Curl-Ribbon
Make sure it's the backing side being scraped across the scissors, not the printed side.
Wade