I made the mistake of installing Katoolin package https://github.com/LionSec/katoolin. The problem is it botched up my Ubuntu, many packages don't work anymore. System update doesn't work anymore.
The question: is there a way to somehow uninstall this from my Ubuntu without re-installing the OS??
PS: Piece of advice to people who want to study computer security: stay away from this Katoolin tool! Think at least ten times before installing it.