1) Download the unroot-update.zip file here - LINK
2) Now copy this unroot-update.zip file into the root folder of your SD Card
3) SHUT DOWN your device and restart it into recovery mode using the following key combination (Volume UP + Home Button + Power Button)4) You cannot use touchscreen while your phone is in recovery mode. To make selections or movements, yuse volume up/down keys and to choose or selecting file use the HOME KEY.
5) In the RECOVERY mode main menu, CHOOSE "apply update from sdcard"
6) then CHOOSE unroot-update.zip and click on "YES".
7) After the patch, you will be back to the RECOVERY MODE MAIN menu, then CHOOSE "reboot system now".
and your done. your device is UNROOTED.
This is only for educational purposes and I will not be responsible for any damages that may happen on your device. Do it on your own risk.