Uninstalling MySQL Community Server on OS X Raw
Tested on 10.7 (Lion) and 10.6 (Snow Leopard).
Remove all startup items, receipts and the MySQL installation directory:
sudo rm -rf /Library/StartupItems/MySQL*
sudo rm -rf /Library/PreferencePanes/MySQL*
sudo rm -rf /Library/Receipts/mysql-*
sudo rm -rf /var/db/receipts/com.mysql.*
sudo rm /usr/local/mysql
sudo rm -rf /usr/local/mysql-*
Remove this in `/etc/hostconfig`
MYSQLCOM=-NO-
Done.