Uninstall Programs Manually

Be aware that these steps may not remove everything associated with the application and can impact other applications on the computer. Have a backup or restore point and use caution.

• Find the directory for the application and delete all the files in the directory. Delete the directory.

• Open regedit and navigate to HKEY_LOCAL_MACHINE\SOFTWARE and find the folder for the application. Delete the folder.

• Open regedit and navigate to HKEY_CURRENT_USER\SOFTWARE and find the folder for the application. Delete the folder.

• To remove the application entry from Add/Remove Programs (if present) open regedit and navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall and find the folder for the application. Delete the folder.

• Some applications have Services attached to them. If this is the case, navigate to HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services, locate and delete the service.

• In Windows Explorer, navigate to the individual user settings and delete program references. Common places to check would be:

C:\Documents and Settings\All Users\Start Menu\Programs and delete relevant entries.
C:\Documents and Settings\All Users\Start Menu\Programs\Startup and delete relevant entries.
C:\Documents and Settings\%YourUserID%\Start Menu\Programs and delete relevant entries.
[Do this for each User ID listed]
C:\Documents and Settings\%YourUserID%\Start Menu\Programs\Startup and delete relevant entries.
[Do this for each User ID listed]

If no entries were found in the previous step and the application launches automatically, navigate to
HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows
and delete the entry.

source: http://www.theeldergeek.com