Clean Uninstall Oracle for Windows

1. Uninstall oracle components using OUI
2. Run regedit and delete the following keys:
Delete the HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE key which contains registry entries for all Oracle products by using regedit.
Delete any references to Oracle services in the following registry location:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\.
Looks for the entries that starts with "Ora" which are obviously related to Oracle.
3. Root the system
4. Delete the Oracle home directory
5. Delete the Oracle Program Files directory
6. Delete the Oracle Start Menu shortcuts directory
C:\Documents and Settings\All Users\Start Menu\Programs\Oracle*
7. Remove Oracle references from the path.
Start -> Settings -> Control Panel -> System -> Advanced -> Environments Variables