How to completely uninstall oracle

1. Shut down all the services starting with oracle
    Computer-Management-Services, stop OracleMTSRecoveryService and OracleServiceORCL services
2. Uninstall the product in Universal Installer, expand all, except OraDb11g_home1, check other items, click Delete
3. Delete the registry and
    enter regedit , open the registry, delete oracle in HKEY_LOCAL_MACHINE\SOFTWARE; delete the content beginning with oracle in
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services; delete all items beginning with oracle in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Eventlog\Application;
    in HKEY_CLASSES_ROOT, delete Items starting with ora
4. Restart the computer, delete the oracle directory, delete the Oracle installation directory app, etc.