Process still stuck in task manager after closing it .

Oops, I've just noticed you are using Sys.WaitProcess() and not Sys.Process()

Here's an example,

function Notepad()
{
    // Assuming Notepad is opened.
    
    var process = Sys.Process("notepad");
    
    // Enter text
    process.Window("Notepad", "Untitled - Notepad", 1).Window("Edit", "", 1).SetText("Smartbear"); // Comment out line
    
    // Close application    
    Sys.Process("notepad").Close();
    
    // Respond to save dialog
    if (Sys.WaitProcess("notepad", 5000).Exists)
    {
        // Click 'don't save' button
        process.Window("#32770", "Notepad", 1).UIAObject("Notepad").Window("CtrlNotifySink", "", 8).Window("Button", "Do&n't Save", 1).Click();
    }
}

1. Launch Notepad, and run the script.

2. Comment out the SetText() line. 

3. Launch Notepad again, and run the script.

The script deals with the 'Do you want to save changes to Untitled?' dialog appearing, as well it not appearing.