Remove Zsh from Ubuntu 16.04
Solution 1:
You can remove it completely with the following command.
sudo apt-get --purge remove zsh
If zsh was your default shell (see How to check which shell am I using? and What is default shell for terminal?), Do Not forget to change it to any other shell before purging, e.g. to bash like this with root access.
chsh -s /bin/bash YOUR_USERNAME
Or below with your login user.
chsh -s /bin/bash