How to remove MySQL Server completely from Mac OS X Leopard

The process isn't deductible so you need to know the files and folders that the MySQL installer changes.

To remove completely, make sure MySQL Server is not running and follow the instructions below:

Part 1:

1 - Open Terminal;
2 - sudo nano /etc/hostconfig;
3 - Enter your password;
4 - Delete the following line: “MYSQLCOM=-YES-”;
5 - Control + X ( to close );
6 - Enter Y ( to save );

--

Part 2:

Open Terminal and run the following commands:

sudo rm /usr/local/mysql
sudo rm -rf /usr/local/mysql*
sudo rm -rf /Library/StartupItems/MySQLCOM
sudo rm -rf /Library/PreferencePanes/My*
sudo rm -rf /Library/Receipts/mysql*
sudo rm -rf /Library/Receipts/MySQL*
sudo rm /etc/my.cnf

Solved!

This solution was found in Tom Keur's Blog.