Erase personal data/apps preserve unlocking and jb 3GS

[Sovicious]

I have an iPhone 3GS(4.3.2)I bought brand new. I did not activate it, unlock it(I'm on tmobile) nor jailbreak(no clue what was used) it myself. I kept intending on updating it never got around to it. I have a new phone so I need to sell(maybe lol) my 3GS. I just want to erase my data off. Can I do that without restoring to factory and then unlocking and jb again as I have no idea how to do that.

[BenderRodriguez]

Don't do Settings->General->Reset
It will brick the phone casing u to restore
The best way is open iTunes and tell everything to sync with the computer(contacts, apps.....) then click sync
Unplug the iPhone plug it back in then go and uncheck those boxes and click sync, now all u should be left with is possibly Mail, Notes and Text Messages