Disabling macOS' System Integrity Protection (SIP)
Apple has introduced a new security feature in Mac OS X El Capitan (10.11) called System Integrity Protection (sometimes referred to as rootless or SIP).
What does it really do? It prevents users, processes, etc. from modifying certain resources on the system (even if you’re running as root).
This is a great security enhancement for the vast majority of Mac users. But, some people need to modify the resources protected by System Integrity Protection.
Even though the security configuration is stored in NVRAM it is easy enough to disable System Integrity Protection (NOTE: The vast majority of users will never need to do this).
Reboot Your Mac
Enter Recovery Mode (hold CMD+R during reboot)
Go to menu Utilities -> Terminal and in the Terminal type:
csrutil disable reboot
The computer will boot and the System Integrity Protection will now be disabled; you’re back to having complete control of your operating system again.
You can verify the System Integrity Protection configuration by entering typing the following in a Terminal: