If you follow the instructions in this post, you should be able to remain rooted and have SuperSU.
http://forums.androidcentral.com/sp...possible-method-root-4-3-a-2.html#post3316246
If that doesn't help, then yes it's possible to unroot, but the Knox indicator has already been tripped, so Sprint and Samsung will be able to tell that you were rooted at some point, and there's no way to reset that. If you still want to unroot, let me know and I'll try to help you through it. I'm working about 14 hours a day right now, so please be patient. I don't get a chance to check back here very often.