Exit superuser mode in terminal

You never were in superuser mode, just a temporarily elevated (sudo) privilege mode that required your admin password.

In Terminal, either typing exit or a control-D will end the current Terminal session. That is what [ Process completed] is advising, and you will need to formally quit Terminal at that point as your Terminal session is over.

Under normal circumstances, your Terminal prompt should not change by running sudo. It certainly does not here using the Zsh shell. If your shell prompt normally ends with a % and it is now #, then press command+D to exit the privileged shell back to your default shell.

You can reset the PS1 Terminal prompt by either quitting and relaunching Terminal, or by running the following command at the Terminal prompt based on the SHELL you are using:

ZSH

source ~/.zshrc

BASH (pick the one where your PS1 prompt setting resides)

source ~/.bashrc
source ~/.bash_profile
source ~/.profile

sudo cd ..

DOES NOT give you a root prompt.

All it does is start a subprocess, run the command "cd .." as root, then the subprocess terminates, because you did not start a shell, and you are back at your normal user prompt.

So when you type 'exit' you are logging out of your normal user account.

sudo will execute the specified command as root, then terminate.

If you wish to stay running as root, then you need to use a sudo command something like:

• sudo -s
• sudo bash -i
• sudo zsh -i
• sudo bash -l
• sudo zsh -l

There are other variations on the theme, but "sudo cd .." is not one of them.

Errata:

Under normal circumstances, your Terminal prompt should not change by running sudo. It certainly does not here using the Zsh shell. If your shell prompt normally ends with a % and it is now #, then press command+D to exit the privileged shell back to your default shell.

Press command+D to exit should read press control+D to exit.

You actually terminated your current shell session. You must close that Terminal window and launch a new Terminal window. When you launch the Terminal app or a new tab/window in the Terminal app...you are put into a new shell session. With macOS when you exit the last shell session associated with a tab/window, then you get that message and the tab/window remains open. macOS does not close the Terminal tab/window once a shell session exits (at least by default settings anyway).

Also, be very careful using "sudo" since it will give you temporary root privileges which can have catastrophic consequences. Even if the command you are using when elevating your privileges is safe, you should only do so if it would otherwise fail with standard user privileges. The command line is very unforgiving and there are no safety nets when using the command line. If you issue a valid command, then that command will be carried out whether it does what you intended or not.

I suggest you review some basic command line tutorials to learn the basics....the basics can allow you to do a lot and may help to become aware of some dangers. Here is one tutorial geared for macOS. Most tutorials will be focused on Linux which is fine since the basic commands & utilities exist on both platforms, however, macOS is still using very old outdated versions of those commands & utilities due to licensing issues so some of their options will not exist on macOS. Plus those Linux based tutorials may have examples for using Linux only frameworks or commands not available with macOS.....macOS will also have their own unique commands/utilities as well. There may be other macOS centric command line tutorials out there:

https://scriptingosx.com/2017/07/first-steps-in-terminal/

I entered superuser mode in terminal using the command "sudo cd .." to add a new command to bash.

That doesn't enter super user [mode]. It just changes the working directory.

sudo temporarily elevates your privileges, but it doesn't change any "mode."