Try to reinstall the program, then uninstall the program. If this does not
work, then delete the Program's folder probably located in the Program Files
folder. Then open up the Registry (Start>Run>Regedit) and navigate to:
HKCU\Software\CompanyName\ProgramName
and
HKLM\Software\CompanyName\ProgramName
Delete the ProgramName key.
But before you do this, you should create a Restore Point with System
Restore. So if anything go wrong with the registry, you then can restore
your system with System Restore.