Install cuda 10.2

1. Uninstall existing nvidia driver

nvidia-installer --uninstall

or

The correct way to uninstall just cuda and keep your nvidia drivers would be:

sudo apt purge "libcublas*" "cuda-*" cuda

Possible, because they were installed as requirements, you can also purge,

sudo apt purge "nsight-*" nvidia-modprobe

After that you can, if you want, also remove the nvidia drivers with:

sudo apt purge "*nvidia*"

Of course, if you installed cuda using nvidia's .run file then this won't work; in that case you probably have some uninstall script.

2. Close X server

# To stop:
sudo init 3
# To resume:
sudo init 5

3. Download & install

https://developer.nvidia.com/cuda-downloads?target_os=Linux&target_arch=x86_64&target_distro=Ubuntu&target_version=1804&target_type=runfilelocal

wget http://developer.download.nvidia.com/compute/cuda/10.2/Prod/local_installers/cuda_10.2.89_440.33.01_linux.runsudo sh cuda_10.2.89_440.33.01_linux.run