proc.CloseMainWindow() 'This is equivalent to clicking the Close button on the title bar.
proc.WaitForExit(5000) 'Give the app up to 5 seconds to exit gracefully.
If Not proc.HasExited Then
proc.Kill() 'Force the app to exit.
End If
If the app has no GUI then just go straight to Kill. If the process is a Windows service then you would use a ServiceController to stop the service instead.