Unrooting Your NOOKcolor
From the Quick Nav Bar, tap Settings and then tap Device Info. Tap Erase & Deregister Device. You will be warned that doing so removes all books and files, including sideloaded content. Then you have a button to do just that. Tap Erase & Deregister Device. Your NOOKcolor erases the data, deregisters, and reboots the device. It is no longer rooted.
As you can see, rooting your NOOKcolor is quite simple and well worth the effort. You can now comparison shop for ebooks (Inkmesh.com), find the best price, and purchase from Amazon, B&N, or Fictionwise and read them on the same device. In addition, you can add other apps easily. Have fun turning your NOOKcolor into a full-fledged tablet!