how to Completely remove Oracle 11g from my computer?

From Manual and Clean Uninstall Oracle for Windows :

1. Uninstall all Oracle components using the Oracle Universal Installer (OUI).
2. Delete the HKEY_LOCAL_MACHINE/SOFTWARE/ORACLE key which contains registry entries for all Oracle products by using regedit.
3. Delete any references to Oracle services/components in the following registry location:HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/. Looks for key entries that starts with “Ora” which are obviously related to Oracle.
4. Reboot the workstation.
5. Delete the ORACLE_BASE directory. (i.e C:\Oracle)
6. Delete the C:\Program Files\Oracle directory.
7. Empty the temp directory.
8. Empty the recycle bin.

http://superuser.com/questions/256762/how-to-completely-remove-oracle-11g-from-my-computer