I'm new to Mac. A friend installed all kinds of additional software including
zsh which I would like to uninstall. So how can I uninstall
If your friend changed the command that shells are opened with, you can change it back to the default login shell from Terminal's preferences:
If the default login shell was changed, you can change it back to
/bin/bash by running
chsh -s /bin/bash.
zsh is included with OS X (in
/bin/zsh), but even if your friend installed a newer version of zsh, you don't necessarily need to uninstall or remove it.