Task Manager Pt.3 - getting an error message after deleting a task (updated)

Updated with a screen screenshot of the error message

Hello,
I am working with the Task Manager Pt. 3 file that Randy posted.
I really like this program he created but whenever I delete a scheduled Task then I receive an error message.
I'm not sure if there is a specific way of deleting a Task that I missed but I watched the video several times.
Please, any help would be greatly appreciated.
Thank you.