// to remove completely

$ apt list --installed |grep nvidia

$ sudo apt purge nvidia*
// nvidia-machine-learning....deb file complains.
// So I purged by
$ sudo apt purge nvidia-compute-* nvidia-d* nvidia-k* nvidia-modprobe nvidia-p* nvidia-s* nvidia-u* xserver-xorg-video-nvidia-* libnvidia-c* libnvidia-d* libnvidia-e* libnvidia-f* libnvidia-g* libnvidia-i*
// to remain nvidia-container-toolkit
// and to remove dependent ones too
$ sudo apt autoremove

$ apt list --installed |grep nvidia
// all gone now
// but, nvidia-container-toolkit also disappeared. (?). It should be reinstalled later.

// download driver from

https://www.nvidia.com/Download/Find.aspx

$ ls
NVIDIA-Linux-x86_64-430.50.run
$ chmod +x NVIDIA-Linux-x86_64-430.50.run

// to prevent complaining about X.org SDK/development package and pkg-config package
$ sudo apt install pkg-config
$ sudo apt install xorg
$ sudo apt install xorg-dev

// now install
$ sudo ./NVIDIA-Linux-x86_64-430.50.run

// reinstall nvidia container. "curl... etc." had been done before.
$ sudo apt install nvidia-container-toolkit
$ sudo systemctl restart docker

// check: not listed with apt since it is installed with .run
$ apt list --installed |grep nvidia

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

libnvidia-container-tools/bionic,now 1.0.5-1 amd64 [installed,automatic]
libnvidia-container1/bionic,now 1.0.5-1 amd64 [installed,automatic]
nvidia-container-toolkit/bionic,now 1.0.5-1 amd64 [installed]