Remove android text prediction and red underline spell checker

After buying new android phone, settings for text prediction and spell checker is turned on by default.
I think its anoyying and i dont want to use any of this feature. I just want simple keyboard, with no text prediction, or spell checker (annoyying red underline), or swipe..

You can turn it off by
Goto Settings  > Additional Settings > Language & Input > Uncheck Spell Checker

and to Turn off predictive Text
Goto settings > Additional Settings > Language & Input > Google Keyboard > Text Correction > Uncheck Show Correction Suggestions and uncheck Next-word Suggestions

But sometimes the spell checker toggle cant be changed in some android phone, like mine in mi4.

Make sure you have rooted your android before continue, you can read here simple guide to root/unroot your mi phone.

Then run terminal emulator (download it in playstore) and then type :
#su

there will be pop up asking for root permission, allow it to grant root access
#settings put secure spell_checker_enabled 0

Boom, you have removed thats red underline. You can reboot your phone if nothing has changed. To turn spell checker again just change 0 value to 1.

Dattebayo..