// Graceful way by process ID var proc = System.Diagnostics.Process.GetProcessById(9836); proc.CloseMainWindow(); proc.Close(); // Force kill by process ID var proc = System.Diagnostics.Process.GetProcessById(9836); proc.Kill(); // Graceful way by partial window title var wnd = sp.WindowsFromTitlePartial("Untitled - Paint").First(); wnd.Process.CloseMainWindow(); wnd.Process.Close(); // Force kill by partial window title var wnd = sp.WindowsFromTitlePartial("Untitled - Paint").First(); wnd.Process.Kill();