http://unrevoked.com/rootwiki/doku.php/public/forever
flash this
How can this be removed or undone if I need to take my phone in for service?
Download
the latest ''S-ON'' tool to a temporary location and follow the installation instructions above to run it. Once your phone is S-ON, you may lose root permanently if you install an official update
Place PC36IMG.zip on the root of your sd card.
Boot the phone into the bootloader by powering the phone down, then press the power and the volume down buttons at the same time.
Once the phone boots into the bootloader the phone will automatically recognize the zip file.
It will ask if you would like to update, select yes and let it do it's thing and you will be good to go
PC36IMG_SuperSonic_S_Sprint_WWE_3.70.651.1_Radio_2 .15.00.11.19_NV_1.90_release_161482_signed.zip (202.01 MB)
MEGAUPLOAD - The leading online storage and file delivery service
MD5 Checksum: 7056D42812AA5DF03FCC8DDDC2B64E85
SHA-1 Checksum: F3725824147B54F4ED917CB025FB5F693B17782B
youll be unrooted and back to stock