so go ahead...
Step No 1: Download vroot windows app from the given link
Step No 2: Install and run it in your Pc
Step No 3: Connect Your Phone Via Usb Cable and check usb debugging option, wait until vroot detects your phone once it's detected click the re-root button ( if you are rooted before ) and now your phone is reboot automatically wait for it to turn on,,,,
now you can see a chiness super su application in your app drawer... don't do anything with this app simply connect your mobile again and check usb debugging option and now click unroot .... Voila you have successfully unroot your mobile
Sorry For My Bad English