ubuntu16.04 uninstall cuda 9.0 completely and install 8.0 instead

卸载cuda 9.0
sudo apt-get --purge remove cuda
sudo apt autoremove
to remove cuda 9.0

Then
sudo apt-get clean
to clear apt-cache

安装8.0
sudo dpkg -i cuda-repo-ubuntu1604-8-0-local-ga2_8.0.61-1_amd64.deb
sudo apt-get update
sudo apt-get install cuda-8-0