1. Ensure you are logged in as a user with Administrator privileges.
Stop all Oracle services.
2. Use the OUI and uninstall products. This is done by selecting Deinstall Products and Oracle Homes - OraHome92 - [x] Oracle9i Database
Then select the [Remove] button.
3. Using Regedit remove all Oracle keys under: HKEY_LOCAL_MACHINE\SOFTWARE HKEY_LOCAL_MACHINE\SOFTWARE\Classes, remove all keys that begin with Ora or ORCL HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\EventLog\Application HKEY_LOCAL_MACHINE\SOFTWARE\ODBC remove all keys related with the "Oracle ODBC Driver"
4. Remove Environment Variables Also remove from PATH all oracle references Example: C:\ORACLE\ORA81\BIN;C:\PROGRAM FILES\ORACLE\JRE\1.1.7\BIN
5. Delete all Oracle Icons from: C:\Documents and Settings\All Users\Start Menu\Programs
6. Delete <system_drive>:\Program Files\Oracle
7. Remove any Oracle-related .INI files that may exist in the Windows directory. Typical Oracle .INI files include ORADIM73.INI, ORADIM80.INI,ORACLE.INI,ORAODBC.INI
8. Reboot your computer.
9. Delete all ORACLE_BASE directories Example: C:\oracle Note: If you attempt to do before the above reboot it will probably show DLL(s) being used.