Sure you can “unfollow” one by one but the easoest way to do it is go to Twitter Karma Sign up and just hit two buttons, one to “check all” and the other to “bulk unfollow”. Sign back up to your tweeter and lo they’re all gone!
If you want to folow your folowers then at the top of the page in the “Show” box chose “only followers” scroll to the bottom , click “check all ” (if you want to follow all) and then click “bulk follow”. That’s it that’s all.