You can do this one of two ways.
1) Download the fastboot files that can be found here:
http://www.droidforums.net/forum/dr...otorola-droid-4-xt894-stock-windows-only.html
There are instructions there as to how to operate fastboot files, and you can do this very easily by following the instructions.
2) you can undo everything manually, which is more complex.
First, download the droid 4 utility to your computer which can be found here:
http://www.droidforums.net/forum/droid-4-hacks/200512-droid-4-utility-windows-mac-linux.html
Go to safe strap and turn safe strap mode to off.
Boot up the phone and uninstall safe strap.
Then plug your phone into your computer by USB, and and open the droid 4 utility and select 2, or unroot.
After this, you'll need to manually remove all files pertaining to root & the apps you have that are root compatible. Go through your list and uninstall them one by one, and open your file manager and remove all the file folders associated with these apps that may still be on your internal SD card.
If you want to make it completely and totally new, open your settings, and go to Privacy, then Factory Reset, then check Erase SD card (this is only if you have an external SD card in the phone, if not, don't select this option), then select Erase Everything.
Your phone will then take a few minutes and reboot, and you'll be prompted to start your phone as if you had just pulled it out of the box.
There you go.
