1- start your PC in safe mode, delete the parent Oracle folder from your drive.
2- Restart in Normal mode.
3- Open the registry using regedit.exe from start/run/
4- delete from the registry the following entries/keys
HKEY_LOCAL_MACHINE/SOFTWARE/ORACLE
HKEY_LOCAL_MACHINE/SYSTEM
Controlset001/services/%oracle_services%
Controlset002/services/%oracle_services%
Now you need clean the legacy entries from your registry.
If your OS is not Win XP you need to use regedt32.exe. If Win XP then use the regedit.exe.
To remove the legacy entries you have to be the Administrator and change the security on the legacy keys so you can delete it.
HKEY_LOCAL_MACHINE/SOFTWARE/SYSTEM/Controlset001/ENUM/Root/Legacy%Oracle_services%
and the same for Controllset002.
I suggest you?d be VERY CAREFUL with the registry, one single mistake and bye-bye Windows.
and also drop the database with dbca before you uninstall the software, and use oradim to remove the services.
