Correctly Uninstall PostgreSQL

Uninstalling PostgreSQL may leave some undesired files. Here’s how to purge it:

First, uninstall all packages from PostgreSQL from the system using

sudo apt-get --purge remove postgresql\*

Then remove all the configuration and library stuff

sudo rm -r /etc/postgresql/
sudo rm -r /etc/postgresql-common/
sudo rm -r /var/lib/postgresql/

And finally, remove the user and group

sudo userdel -r postgres
sudo groupdel postgres