twitter_unfollow.py

import tweepy
from   time import sleep

# Unfollows all users that aren't following you back.
# Twitter's rate-limiting allows about 800 unfollows per session.

SCREEN_NAME = "YOUR_TWITTER_HANDLE"

# Twitter Auth
auth = tweepy.OAuthHandler("", "")
auth.set_access_token("", "")
api = tweepy.API(auth)

followers = api.followers_ids(SCREEN_NAME)
friends = api.friends_ids(SCREEN_NAME)

for f in friends:
    if f not in followers:
        print ("Unfollowed {0}".format(api.get_user(f).screen_name))
        api.destroy_friendship(f)
        sleep(0.25)