How uninstall droidboot? +back to full original condition zenfone 5

Hi, i have Zenfone 5 with stock rom "2.19.40.18" KK 4.4.2

How uninstall Droidboot??

I have been problem with GSM signal and this problem isn't solved. I want return back this phone to Asus while i have warranty.

Thank you for help :)