These are the steps to unroot Samsung Galaxy S3 Alpha SC-03E smartphones by flashing the official stock ROM back on the device. The DoCoMo variant of the Samsung Galaxy S3 is prominent in Japan. Using this guide, you can easily flash the stock ROM and return the smartphone to the way it was when you first opened it out of the box.
- Your Samsung Galaxy S3 Alpha with the model number SC-03E should be rooted  before you follow this guide.
- You need the Samsung Galaxy S3 Alpha from Japan with the model number SC-03E to follow this guide.
- You must have a Windows computer to follow this guide to unrooting your S3 with the Odin app on computer. The Odin app only runs on a computer running Windows operating systems.
BEFORE WE BEGIN
- You should backup the data on your Samsung Galaxy S3 Alpha before starting this guide. Always make a backup before customizing or unrooting a device so you can restore your data later if you need it.
- You will need the USB Debugging Mode enabled again before you can use this guide since we are connecting the Samsung Galaxy S3 to the computer and using the Odin flashing tool.
- Start off by unlocking the hidden Developer Options menu if you haven’t already by tapping on the Menu > Settings > About Device > Build Number seven times and it will tell you that you are using the S3 as a developer.
- Enable the USB Debugging from the Developer Options you just unlocked by tapping on the Menu > Settings > Developer Options > USB Debugging Mode.
- Download the Samsung USB Drivers  directly to your computer so your Sammy S3 handset can talk with your computer and the apps you are running on the computer to flash the files.
HOW TO UNROOT SAMSUNG GALAXY S3 ALPHA SC-03E
- Download the Samsung Galaxy S3 SC-03E stock ROM from this link .
- Download the latest Odin flash tool from this link .
- Extract the two files on the desktop by right-clicking and choosing the “extract here” option from the menu.
- Tap on the Power button > Device Options and choose to Power off your Samsung Galaxy S3 smartphone.
- Reboot the Samsung Galaxy S3 DoCoMo smartphone in download mode .
- Connect the Samsung S3 from Japan to the computer using the USB cable.
- Click the PDA/AP button you can see from the Odin user-interface.
- Browse the desktop and upload your extracted stock ROM for the S3.
- Click the Start button and the Odin app on the computer will flash your stock ROM.
- Unplug the Samsung Galaxy S3 DoCoMo from the computer once you see the Odin user-interface is giving you the pass message and your S3 reboots automatically.
Those who do not see the Samsung Galaxy S3 DoCoMo smartphone root will need to do that manually now before installing apps from the Google Play Store.
As soon as the S3 smartphone does reboot, you are ready to start installing any of the apps which require root access to run like the Titanium Backup application. Those who would like to taking backing up the device a step further might be interested in installing a custom recovery on the Samsung Galaxy S3 DoCoMo smartphone so they can start taking NANDroid Backups.