If you mean how to return it to factory settings: Options>Security>General Options>BB Key> Wipe Handheld.
This will wipe ALL extraneous data from the device, returning it to the state you received it in. If there is info on the device you wish to keep, I would suggest a backup first.
There's a couple ways.
1. You can wipe the phone completely with JL, or Crackmem I believe it is.
2. There's another way on your phone to start wiping it, not too sure right now. But the easiest way is put in the wrong password a few times, and it'll wipe it for you.
If u do a wipe and then a backup to put back all ur contacts and all that other good stuff. Will the os be .75 or the last os u had? I'm just wondering cuz I had to return my original storm cuz of a cracked screen and I've done a few os upgrades but nothing works as great as it did on my original storm. So I dunno if my storm is all effed up from all these upgrades. I even tried to dl a hybrid but didn't work. I'm getting o frusturated with this thing!
Posted from my CrackBerry at wapforums.crackberry.com