If you want to shut off your mobile data you have to do this:
Swipe down from the top of the screen, select Settings, press Data usage and then flick the Mobile data switch from ON to OFF - this will completely turn off your mobile data connection. Note: you will still be able to connect to the internet and use apps as normal if you are connected to a Wi-Fi network.
If your phone is having error messages like that you have to reflash your SuperSU.zip file in your recovery.
Here's the link for the SuperSU.zip to flash in your recovery.
https://download.chainfire.eu/696/SuperSU/UPDATE-SuperSU-v2.46.zip?retrieve_file=1