you can use this script to unfriend selected friends from facebook friends. This is very useful script for the aspirants who will regularly work with facebook.

Advantages of this Facebook Trick:

Delete Facebook friends fast.
Delete all Facebook friends at once.
Delete all Facebook friends in one click.
Delete multiple Facebook friends.

You can clearly read step by step Guide about How to unfriend selected friends with a single click in Facebook - @ Lopa Mudra

Note :

1. Please note that the script may not load at the first load the page, So do a hard refresh (Ctrl + F5) and refresh the page couple of times until you can see the additional buttons of the script.
2. Using scripts with Facebook is an unofficial process. This is only for educational purpose. This script can be used and can be shared with your friends at your own risk.