Red face [Q] root unroot sprint galaxy note 3

New to all of this.
Can someone please, please help.
I rooted my phone. Sprint Galaxy Note 3.
I rooted it for only 1 reason and that was to get free wifi tethering. I have no idea which wifi tether works I have no idea. It's rooted but I need a wifi tethering app that works for sprint.
Also if I need to turn in the phone for warranty how do I unroot.