How to unroot Android phone or tablet: Return to factory settings
If you’ve finished experimenting with ROMs and Root access, then there is a simple was to take your phone back to the way it was when you began. Open up the SuperSU app, go to Settings and then select the Full Unroot option. Hopefully now your device will return to its unrooted status.
If this doesn’t work then you can still unroot your phone, but it will involve researching your particular handset and maybe asking a few questions on the XDA Developers forums. They’re a friendly bunch though, so it’s not a bad way to spend some time.