How do I unroot my Xiaomi mi3 device

Jul 9, 2014
As the heading suggests kindly let me know how do I unroot my Xiaomi mi3 device back to its original factory condition. In my rom it shows in brackets stable build... Does it mean my phone isn't rooted? Just for your info I clicked on select update package and had installed 2-3 roms
Right now it says in bracket stable build.. Kindly tell me how to unroot my phone and get it back to original factory settings with all official software. Thanks