Important
Just to be safe you NEED to revert to stock FIRST BEFORE YOU UNROOT. Why? because if something happens and you get stuck in a bootloop you wont be screwed. of course make sure you still have CWM installed and have a BACKUP on hand as normal. Have 2 just incase
LETS GET STARTED
Here is the unrooter
http://androidforums.com/esteem-all-things-root/436718-unrooter-download.html
But as far as 100% stock? You can downgrade to B then upgrade back to D but its gonna take you about an hour and a half total time.
-OR you can do this and this is easier and will save you a lot of time.
Download
www.androidcommander.com
Then download the stock ZIP for your software version. B, C or D
http://androidforums.com/esteem-all-things-root/513323-esteem-stock-pulls.html
Then unzip the zip and save it on your desktop.
Put your phone in internet connection with usb debug on. Open commander.
Make sure your phone files are "Mount R/O". you can do this through root explorer on the top right of the app. It should be R/O but gotta make sure or you cant paste anything to the phone.
Once commander is open you will see a split window. On the left is your computer files and on the right is you phone files.
What you can do is push all the "stock" files from the zip over to the right side (the phone). Reboot and your phone will be 100% stock with no root.
(Just "drag" the files over to the right side from your desktop. A pop up will come up and ask you where. Choose "right side". Once you finish dragging all the files over jsut reboot the phone. Phone should boot up just fine. I've done this several times before. BUT if it boot loops for whatever reason. Boot into CWM or you can just click reboot recovery in commander. Commander will recognize the phone once it starts to boot so you will be able to choose it even know the phone isn't booted up.)
I hope all this helps. If you have any problems just send me a PM and Ill do what I can. You should be okay as long as you follow the directions carefully. Remember MAKE A BACKUP and DONT UNROOT FIRST.