"- The best way to uninstall the version you mistakenly installed is to use the terminal application.
Do the following in terminal:
1) cd /usr/local (change directory to...)
2) ls -l (directory listing)
you should see a directory listing for /usr/local. You should see an install directory for mysql called something like "mysql-standard-5.0.19-osx10.4-powerpc" (that is what mine looke like). You will also see a symbolic link (like a shortcut shortcut) "mysql -> mysql-standard-5.0.19-osx10.4-powerpc". This is just an alias to the long directory name.
3) sudo rm -R mysql-standard-5.0.19-osx10.4-powerpc (you will have to enter your administrator password - this is the password for your main mac account that you set up when you installed your OS or first set up your machine.)
4) ls -l (verify that the directory is gone)
That should do it for you. Reinstall the correct MySQL package for your OS version after you have deleted your other mysql directory -"