This guide instructs on how to UNROOT your phone, manually (not using S1C or Z4, or a similar program).
First, the files you will need.
1. Samsung drivers
3. Stock 2.1 image
4. some form of file explorer on your phone. I use root explorer, but that is paid. Another (free) good one is es file
What to do. (NOTE: This tutorial assumes that you do not already have samsung drivers or odin, if you do, then ignore the first two steps)
1. Install the Samsung drivers
2. Unzip odin and extract to your desktop
3. Open odin, and click the PDA button, find Continuum-Stock-DL17.tar.md5 and select it.
4. Place your phone into download mode, and plug into your computer, making sure you have a good COM.
5. make sure repartition is UNCHECKED and auto reboot is CHECKED
6. click start.
7. after your phone reboots, go ahead and set it up. You are still rooted, at this point.
8. download the file explorer of your choice, and install it.
8 A. if using ES file, open the app, then click menu, and settings. Scroll down to 'home directory', where it is set to /sdcard. erase the 'sdcard' part so that all that is there is '/'. Then scroll down to 'mount system as rewriteable' and check it.
9. go to /system/apps and delete superuser and superuser update fixer (if you have that installed)
10. back out to /system and go to /system/bin and delete su
11. back out to /system and go to /system/xbin and delete busybox.
you now have a successfully unrooted phone.
NOTE: This does a reset on your phone, all personal data will be lost, and you cannot rely on Titanium back up to restore it, unless you restore BEFORE deleting superuser and busybox
Again, please ask any questions before you start the process.