To uninstall a MySQL where you have used the MSI packages, you must use the Add/Remove Programs tool within Control Panel. To do this:
Right-click the start menu and choose Control Panel.
If the Control Panel is set to category mode (you will see Pick a category at the top of the Control Panel window), double-click Add or Remove Programs. If the Control is set to classic mode, double-click the Add or Remove Programs icon.
Find MySQL in the list of installed software. MySQL Server is installed against release series numbers (MySQL 5.1, MySQL 5.5, etc.). Select the version that you want to remove and click.
You will be prompted to confirm the removal. Clickto remove MySQL.
When MySQL is removed using this method, only the installed components are removed. Any database information (including the tables and data), import or export files, log files, and binary logs produced during execution are kept in their configured location.
If you try to install MySQL again the information will be retained and you will be prompted to enter the password configured with the original installation.
If you want to delete MySQL completely:
Delete the associated data directory. On Windows XP and Windows Server 2003, the default data directory is the configured AppData directory, which is
C:\Documents and Settings\All Users\Application Data\MySQLby default.
On Windows 7 and Windows Server 2008, the default data directory location is
C:\ProgramDatadirectory is hidden by default. You must change your folder options to view the hidden file. Choose , , Show hidden folders.