Step 12: Install SuperSU the same way that you got to install Safestrap, now once installed it will ask you to update Binaries, say continue, then it will ask via Normal or TWRP/CWM, say Normal...It will try and disable the other SuperSU too, and fail, and it will disable Knox...sure...
Step 13: Go into Chainfire's SuperSU > Settings > scroll to the bottom and click the "Switch Superuser App", it will promptly uninstall itself.
Step 14: Reboot and at this point Safestrap should be enabled and boot into Recovery when you see the Crazy little robot guy
Step 15: From here install SuperSU again and reboot. When the phone reboots the Chinese version of SuperSU should be gone with just Chainfire's version