Delete /usr/bin/emacs - Operation not permitted

I was about to reinstall Emacs from railwaycat/emacsmacport when I stumbled upon /usr/bin/emacs, /usr/bin/emacsclient and /usr/bin/emacs-undumped.

angrybacon@sandman ~/ $ ll /usr/bin/emacs*
-r-xr-xr-x 1 root wheel 26929904 Dec  3 07:35 /usr/bin/emacs
-rwxr-xr-x 1 root wheel  3201184 Dec  3 07:36 /usr/bin/emacs-undumped
-rwxr-xr-x 1 root wheel    36928 Dec  3 07:36 /usr/bin/emacsclient

I'm trying to delete those binaries with no success.

angrybacon@sandman ~/ $ sudo rm -f /usr/bin/emacs*
rm: /usr/bin/emacs: Operation not permitted
rm: /usr/bin/emacs-undumped: Operation not permitted
rm: /usr/bin/emacsclient: Operation not permitted

I've tried GNU's rm and removing schg flag, still no luck.

Also, are those shipped with default Mac setups?

Same issue with /usr/share/emacs/ and /usr/share/info/emacs*.

It's the new "system integrity" feature in OS X. Even as root, you can't do everything. Good news is... you can disable it.

1. Reboot into recovery mode (boot while holding down command + r keys.
2. Open the terminal (Utilities -> terminal)

3. run the following in the terminal:

   csrutil disable; reboot
   

Hit return, your mac will reboot and you'll be good to go.