Delete system app using zip file
Part 1 Unrooting Your Device

You can unroot your phone from SuperSu itselef

Go to SuperSu > Setting > Fullunroot.

Part 2: Replacing KingUser

You can download the ready to use script for replacing it with SuperSu Here


Download Zip file from site
Extract it in External Sdcard
Launch Terminal Emulator
Type su and give the superuser acess
Type sh /sdcard/mrw/root.sh
Script will automatically delete all Kinguser files amd will make SuperSu as system app
Update SuperSu binary