In order to root the Barnes & Noble NOOK Tablet you need to connect the tablet to your computer with a USB cable and run a series of commands in a terminal or DOS box. But if you want to unroot the tablet there’s now a way to do it with an Android app.
The app will also reformat the system partition of your device, which will erase all of your data. If you want to unroot your tablet so you can sell it or return it to Barnes & Noble, that’s a good thing. But if you’re unrooting for another reason you’ll probably want to backup your apps using Titanium Backup or a similar tool before unrooting.
Once you’re ready you can download the NOOK Unroot APK from the xda-developers forum and install the app on your tablet.
Then all you have to do is fire up the device and click the “Unroot Device” option. It’s not actually a one-click app, because you have to click “continue” before the process starts and then reboot your device once the app is finished.
But unrooting and performing a factory reset doesn’t get much simpler than this.
Note that if you really do want to erase everything from your device you may still need to manually delete files and folders from the storage partition on your NOOK Tablet.
If you’re looking for a way to unroot your tablet without reformatting the system partition, you can do it manually by running a script from your computer.