Again, the vast majority of Mac users should not disable rootless. Disabling rootless is aimed exclusively at advanced Mac users. Do so at your own risk, this is not specifically recommended.
csrutil disable; reboot
You’ll see a message saying that System Integrity Protection has been disabled and the Mac needs to restart for changes to take effect, and the Mac will then reboot itself automatically, just let it boot up as normal
You can also issue the command by itself without the automatic reboot like so:
csrutil disable
Checking the Status of Rootless / System Integrity Protection in OS X
If you want to know the status of rootless before rebooting or without rebooting the Mac into recovery mode, just issue the following command into the Terminal:
csrutil status
You’ll either see one of two messages, enabled indi:
$ csrutil status
System Integrity Protection status: enabled.
or
$ csrutil status
System Integrity Protection status: disabled
If at any time you wish to change the status of rootless, another reboot into Recovery Mode is required.
How to Re-Enable Rootless System Integrity Protection in OS X
Simply reboot the Mac again into Recovery Mode as directed above, but at the command line use the following syntax instead:
csrutil enable
Just as before, a reboot of the Mac is required for changes to take effect.
As previously stated, the vast majority of Mac users should leave rootless enabled and embrace System Integrity Protection, as most OS X users have no business in the system level directories anyway. Adjusting this feature is really aimed at advanced Mac users, whether IT, sysadmins, network administrators, developers, tinkerers, security operations, and other related highly technical fields.