This script will cleanup your following list on Twitter. https://sferik.github.io/t/ needs to be installed.

twitter-cleanup.sh

#!/usr/bin/env bash
#
set -o nounset
set -o errexit

KEEPFILE=`mktemp /tmp/$(basename $0).XXXXXX`
KEEPLIST='Reading'

# create list with people who should not be removed in any case:
t list members $KEEPLIST | sed 's/ /\n/g' | sort -f > $KEEPFILE

# unfollow everyone who is not following back
# every user in $KEEPLIST is filtered from the list
t leaders | sed 's/ /\n/g' | grep -v -f $KEEPFILE | xargs -I {} t unfollow "@{}"

rm $KEEPFILE