1: Turn off all Oracle services. Can be turned off in server management for Windows.
2:window+r Open the Run command line, Regedit opens the registry and finds the path hkey_local_machine\system\currentcontrolset\services\ Delete all service names starting with Oracle under this path.
3: Locate the path hkey_local_machine\software\oracle delete the Oracle directory, which registers the software installation information for the Oracle database.
4: Find the path hkey_local_machine\system\currentcontrolset\services\eventlog\application Delete all items in the registry starting with Oracle, That is, the registered Oracle event log is deleted.
5: Delete the environment variable in path about Oracle content. Right-click My Computer--Properties--advanced--environment variable-->path variable to delete the contents of Oracle in this variable. Note: A directory of operating systems is recorded in the path variable, separated by semicolons (;) between directories in Windows, and should be noticed when deleted.
6: Restart your computer
7: After restarting the computer, all processes related to Oracle are not loaded, and all data under Oracle_home is removed (Oracle_home refers to the installation directory of the Oracle program).
8: Delete the Oracle directory under Program files in drive C (this directory depends on the installation directory).
Win8 the computer above completely remove oracle11g