In response to a question on stackoverflow, here is a short guide on how to completely uninstall PostgreSQL 9.1 from Mac OS X Lion.
- Open a terminal window
- Run the uninstaller
- Remove the PostgreSQL and data folders (Wizard will notify you that these were not removed)
sudo rm -rf /Library/PostgreSQL
- Remove the ini file
sudo rm /etc/postgres-reg.ini
- Remove the PostgreSQL user
System Preferences -> Users & Groups
Unlock the settings panel by clicking on the padlock and enter your password
Select the PostgreSQL user and click on the minus button.