2024 Updated Script @epicisdaddy

• Open news feed preferences on your Facebook menu (browser)
  

• Click people or pages
  

• Scroll down (or click see more) until your full list is loaded
  

• Run the script in your browser console
  

Facebook will block this feature for you while you use it, depending on how much entities you try to unfollow. It automatically unblocks in a couple of hours and you will be able to continue.