I accidentally installed the PowerPC version of MySQL on my Intel Mac in Snow Leopard, and it installed without a problem but of course doesn't run properly. I just didn't pay enough attention. Now when I try to install the correct x86 version it says that it can't install because a newer version is already installed. A Google query led me to perform these actions/delete these files to uninstall it:
sudo rm /usr/local/mysql
sudo rm -rf /usr/local/mysql*
sudo rm -rf /Library/StartupItems/MySQLCOM
sudo rm -rf /Library/PreferencePanes/MySQL*
rm -rf ~/Library/PreferencePanes/MySQL*
sudo rm -rf /Library/Receipts/mysql*
sudo rm -rf /Library/Receipts/MySQL*
And finally removed the line MYSQLCOM=-YES- from /etc/hostconfig
They haven't seemed to help at all. I am still receiving the same message about there being a newer version. I tried installing an even newer version (the current Beta) and it also gave me the same message about a newer version already being installed. I can't uninstall it from the Prefs Pane because I never installed the PrefPane also.
Try running also
sudo rm -rf /var/db/receipts/com.mysql.*