Removing Root for Sony SP A while ago, I decided to root my Sony Xperia SP (c5303) the downfall is that the operating system it's self was stuck on Android 4.1.2 with the build number of 12.0.A.2.254, now the time has changed and I wish to remove the root and update to the latest android version available for the phone which is currently 4.3 to my knowledge. I have lost the tools which I used previously to root the device it's self &amp; Have found a few threads on the XDA Forums containing a few stock ROMS, the only tool which I have managed to find is the flash tool for old phones models of the 2011 family (MT15I for example) 

With trying both the OTE update and the Companion update options, they both fail. Companion gives the error stating that 


  Software cannot be modified 


I'm assuming this is fired from the Super User application which was installed on the root. 

I'm at a block on how to proceed further after looking over google for unrooting methods, they all revolve around clockwork mod to install a custom ROM, this is not present on my device.

So the question i'm asking today, is that are there any viable methods on how to unroot the device and upgrade to android 4.3? Using the Sony Tool emma seems to be out of the question as it's not letting me create an account to use their tools!
You can try repair option in Sony PC companion or SUS(Sony Update Service). If none of this works try the steps given below

Download the ftf file from here. 

Using flashtool flash the ftf. The tutorial on flashing can be found here