After unlocking bootloader every boot bothers us by showing warning in red letters.
Here is how to remove that :
You will need mfastboot, adb, bootlogo - all.
I'll take no guarantee for bricking your device if you are doing something wrong!
If you have path of adb and mfastboot added to system variables, just shif+right click in the folder where logo file resides. Choose 'open command prompt here'.
Otherwise, copy logo file to mfastboot directory and open command prompt there.
Run theses commands:
adb reboot bootloader mfastboot flash logo logo_fixed.bin mfastboot reboot
If you wish to create your own boot logo, then head to this :