To enable auto logins on the TTY running on any serial port on the Controller log in and run the following command and reboot.
sudo sed -i "s#agetty --keep-baud#agetty --autologin pi --keep-baud#" /lib/systemd/system/serial-getty@.service
And to disable it run the following command and reboot.
sudo sed -i "s#agetty --autologin pi --keep-baud#agetty --keep-baud#" /lib/systemd/system/serial-getty@.service
To login automatically using a different username replace the "pi" username in the above commands.
When enabling this all users with access to the Controller Pi serial port will be able to log in without any authentication.