See comments section for more up-to-date versions of the script. The original script is from 2014 and will not work as is.
- 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.



@zeeatsh I'm glad the script worked for you. However, unfortunately, I see no way to unfollow/unfriend friends from the activity log. It may be possible from public profile page, but it would be a pain to create and maintain considering how Facebook CSS classes are minified. I mean, what is this?
There's no gaurentee these classes will remain consistent for more than two days. I wrote a script for me that worked that day, two days later, everything is broken. Point being, this sort of task may have to be done with an application made by C# that uses Facebook APIs. Hopefully, someone creates that soon.