remove and reinstall docker code example

Example 1: Package 'docker-ce' is not installed, so not removed

sudo rm -rf /var/lib/docker /etc/docker
sudo rm /etc/apparmor.d/docker
sudo groupdel docker
sudo rm -rf /var/run/docker.sock

Example 2: Package 'docker-ce' is not installed, so not removed

dpkg -l | grep -i docker