You need to flash the KitKat factory image.
https://developers.google.com/androi...es#razorktu84p
Once downloaded, you need to install Fastboot on your computer. This is probably the easiest way:
[TOOL] [WINDOWS] ADB, Fastboot and Drivers -… | Android Development and Hacking | XDA Forums
You'll need to add Fastboot to your system's path. You can skip to the part about that here:
How To Set Up Android ADB & Fastboot On Windows [Tutorial] | Redmond Pie
Then, extract the factory image you downloaded. You will need to unlock your bootloader. Boot your device into the bootloader by holding power and volume down when the device is off. Plug your tablet into your computer and run "fastboot oem unlock" at a command line.
This will wipe all your data. Then run the "flash-all.bat" file that is inside the factory image.