Hard Reset SONY Xperia Z Ultra C6802

First method:

1. Power on the phone.
   
2. Then goto Settings -> Backup & reset -> Factory Data Reset -> Reset Phone.
3. Now select option "Erase everything", and confirm that.
4. Done!

Second method:

1. First you should download flashtool from Sony website:http://developer.sonymobile.com/services/flash-tool/
2. Make sure, that you have installed drivers for your USB data cable.
3. Now turn off your device.
   
4. Then press and hold Volume Down, and connect to USB cable.
   
5. Next follow the instructions in your screen, and accept appropriate options.
6. Success!

Third method:

1. Back up your important files, and download PC Companion from here:http://www.sonymobile.com/gb/tools/pc-companion/
2. After installation you will see window with 4 options.
   
3. Now hover your mouse over the option "Support Zone Now!" and click "Start".
   
4. Next plese wait, until your program Install a suitable additive.
5. Afterwards from the window with 3 options choose "Phone / Tablet Software Update", and click "Start".
   
6. Then click to "repair my phone / tablet".
   
7. Accept all informations.
   
   
8. Now your program will run "preparing computer for software update".
   
9. Select your model.
   
10. After that you will see window with informations.
    
11. Follow the instructions, and connect your device into your Personal Computer.
12. Success!

WARNING !
Hard Reset will erase all of your data
All described operations you are doing at your own risk.