I will explain How to root Sony Xperia Z C6602 and C6603?
The first thing that you need to do is download the Easy Rooting Toolkit.
Then take your phone, click on Settings >About phone and then click on the Build number five times to get Developer options allowed. Now tap on Developer options, tap on the switch to switch it on and confirm allowing development settings. Now you have to allow USB debugging. After that, go into Security, and under the „device administration“, click Unknown sources box.
On your computer, make sure that any ADB software is switched off so
they do not interfere with the rooting process. Go to the folder where
you downloaded the Easy Rooting toolkit, extract the whole folder and
connect your phone with your PC via the USB cable. Click the Runme.bat
file in your Easy Rooting toolkit, press enter and the rooting should
start. A restore screen will appear on your phone: simply press „Restore my data“. Once it has restored, you need to press the following combination: *#*#7378423#*#*
Now go to Service tests>Display. When your display turns white,
press enter on your computer and wait a couple of moments while it
finishes. You will be asked to enter your PIN code on the phone and
then the process should be completed and you will be able to find
Superuser among your apps.
If you want to check if you have successfully completed the whole procedure, you can download this file and check it !!!