Installation of the JDK on Microsoft Windows Platforms

Sometimes, attempts to uninstall JDK through the Windows
Add/Remove program leave behind some Java entries in the
registry that are not fully removed. These left behind registry entries can cause
problems in installing a new version of Java. The following are the methods to
cleanup registry entries:

• Program Install and Uninstall troubleshooter (Recommended
  Method)
• Manual Registry Edit

Program Install and Uninstall troubleshooter (Recommended
Method)

Run the Program Install and Uninstall
troubleshooter to repair the corrupted registry keys that prevent
programs from being completely uninstalled, or blocks new installations and updates.

Manually edit the registry (Use this only if the Fix It utility
does not work)

Incorrectly editing your registry may severely damage your system. You
should back up any valued data from your computer before making changes to the
registry.

To save the registry key before deleting, in the menu bar, select
File and then Export. In case you
deleted the wrong registry key, you can restore the registry from your saved backup
file by selecting from the menu bar File and then
Import .

To delete the registry key:

1. Determine the correct Registry Key. See Finding the JDK Registry Key and UninstallString
   Value.

2. Highlight the key, Right click and select
   Delete.

3. Click Yes when prompted.

The JDK gets uninstalled.