Default Unrooting Rogers Galaxy S4

Hello,
I managed to Root my Galaxy S4 but now I have to send my phone in for repairs. I tried to UnRoot with Mobile Odin Pro and I am getting IMPORTANT Using Mobile ODIN on this device will VOID YOUR WARRANTY, as KNOX counter will be triggered...
Does anyone know how I can unroot my phone? I am running Android 4.3 on Rogers SGH-I337M.

Thanks,