I just want to clean my Facebook news feed and start from crash adding my friends back.
What is the fastest way can I remove all friends from news feed?
Officially, you have two possible courses of action:
Unofficially, you could use a Greasemonkey script like this one.
Disclaimer: I have not used this myself and cannot verify its effectiveness.
Search for any userscripts here and run it with Greasemonkey [Firefox] or Tampermonkey [Chrome]
Not sure if facebook timeline cleaner userscript still works, I tried using the script mentioned in this website and I think it may help you.