Help!My phones rooted and i want to unroot it

[drel1989]

Let me just start with im new to this whole rooted phone stuff.I want to update my HTC Sensation 4G to ICS but its rooted.i downloaded CID Getter my cid is [t-mob010] i also had downloaded an app that told me it was rooted.i just want to know how i can unroot it or make so i can update it to ICS. someone please help!