csrutil disable "command not found"
As everyone else has pointed out, check your syntax/spelling.  Here is much more info regarding SIP and csrutil. 

Are you sure the recovery volume you used is 10.11?  If you booted from internet recovery, it will bring you to the OS that shipped with your device.

Finally, remember that any status set via csrutil will be erased upon NV clear.  There is really no 'permanent' way to set it.