I feel it's only purpose is ego inflation. Everyone with a Twitter account has a Klout score which is also dumb. Unfortunately, Klout initially did not allow you to deactivate or opt out of having a Klout account. Now you can. Go to you profile page: http://klout.com/#/edit-settings/profile
Find the link on the bottom that says "Delete My Account" and enjoy not being a total knob.
You are welcome internet.