Need Help Unrooting Galaxy S3

I need to send my S3 off for a repair but need to unroute it first
ive tried looking everywhere for my original stock file but cant seem to locate it
Ive got
GT-19300 International – Virgin Mobile
Answer #1
if you have root acces with SuperSU inside the app itself you have unroot option
Answer #2
You’ve got to use Triangle away and a stock rom.
Answer #3
You've got to use Triangle away and a stock rom.
I guess he doesn’t need to use triangle away!
Just flash the stock rom via PC ODIN and he is done!
And don’t forget to wipe everything through recovery if you want to avoid any problems!
Answer #4
Also one of the best sites for everything android check out http://forum.xda-developers.com/
They have anything you need from tools to custom roms to all kinds of guides to unrooting and improving anything.
Answer #5
Is it still under warranty?