If you never modified your Droid X other than rooting it so you can use it wireless tether or other apps that need root - OR if you made a nandroid backup right after rooting and you can restore that backup, then the following process is the easiest one I have found (and just used) to unroot my Droid X. Note: This information was pulled from the Droid 2 forum and I take no credit, except for the extra detailed notes.
First off, if you rooted and made a Nandroid backup right after rooting, restore that backup. If you never used custom roms, etc, then don't worry about that part (just rooted to use some apps that require root).
Download a Terminal Emulator app from the marketplace.
- open your trusty terminal app (that's the terminal emulator you downloaded)
- you should see a $ symbol, now do the following (type each line exactly as writen after the "-" but do not type what is in the parenthesis)
- su (give a minute to ask for Superuser Permission. If it doesn't ask, go into Superuser Permissions and grant access to your Terminal Emulator and go back and retry this step)
- now you should see a # symbol (after each of the following steps is processed, you will see a #)
- mount -o rw,remount -t ext3 /dev/block/mmcblk1p21 /system
- rm /system/app/Superuser.apk
- rm /system/bin/su
- rm /system/bin/busybox
- mount -o ro,remount -t ext3 /dev/block/mmcblk1p21 /system
- reboot your phone. Tada, no more root! To prove this, try opening wireless tether or another program needing root access and you will be rejected.
If anyone notices anything wrong on here, please let me know. If this was posted elsewhere in the DX forum area, I apologize for reposting, but I couldn't find it. I just wanted to make this easy for people to find.