I need to stop the GUI and access a TTY for the NVIDIA drivers. I found this question. However, when I tried sudo service lightdm stop (or the same with gdm), it said this:

$ sudo service lightdm stop

Failed to stop lightdm.service: Unit lightdm.service not loaded.

$ sudo service gdm stop

Failed to stop gdm.service: Unit gdm.service not loaded.

I'd prefer not have to mess with Grub, as I only need to stop the GUI once. So, how do I stop the GUI to use a TTY with no GUI running at all in Kubuntu 21.10?

Note: I know how to access a TTY. But once I'm in the TTY, I need to stop the GUI, as the NVIDIA driver installer wants me to be in a TTY and have the GUI not running.