Awesome, it works. Thanks! Notes: first go to facebook.com > arrow in upper right > Settings & Privacy > News Feed Preferences > and scroll the whole list

Awesome, it works. Thanks! Notes: first go to facebook.com > arrow in upper right > Settings & Privacy > News Feed Preferences > and scroll the whole list to the bottom open your console and run the script, and wait. The script takes 1.5 seconds per each "unfollow", so if you have 500 for example, it will take more than 8 minutes :)