I am using Oracle 10 Gb because I encountered this problem, so I sent this to the Internet to share with you hope to bring you some convenience!
Uninstall procedure:
1. Start-> set-> Control Panel-> Administrative Tools-> services-> stop all Oracle services. (You don't need to stop it if it's not started)
2. Start->Program-> Oracle-oradb10g_home1-> Oracle Installation products-> universal Installer
Uninstall all Oracle products. (do not click Next. click the button on the top to uninstall the product !)
3. Run regedit, select HKEY_LOCAL_MACHINE \ SOFTWARE \ oracle, and press del to delete the entry. If it is another disk, find it and delete it!
4. Run regedit and select HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Services. Scroll through the list and delete all Oracle entries.
5. If you use the default directory named Oracle under drive C, delete it!
6. restart the computer to completely delete the Oracle directory.
7. Delete Oracle-related files, select the default Oracle directory c: \ oracle, and delete the entry directory and all subdirectories,
And delete the following files from the Windows 2000 directory (generally c: \ WINNT)
Oracle. ini, oradim80.ini
8. If there is a [Oracle] Tag segment in the win. ini file, delete it.