What happens if you go to the address in the email? What happens if you go to the _layouts/settings.aspx URL corresponding to the site/site collection linked to? You need to find where the actual workflow is stored (clue is the link in the messages) and then use SharePoint Designer to access the Workflow list, where you should be able to deal with it.

In terms of changes to the script, it should be possible to display the details of each alert found for a given user. in fact I think when I was originally writing the script I did this as part of my debugging, but removed from the final version as I didn’t want or need that level of verbosity.

The yes/no functionality is much more of a challenge in PowerShell. I am sure you can do it, but you may find it is not worth the effort where you only occasionally want to delete a specific alert for a specific user. My use case was something I was doing a couple of times a month to get rid of alerts for staff who had left – I didn’t particularly care which alerts I was deleting.

I’d be delighted if you used my script as the basis for resolving your specific issue. If you do, please share with the wider SharePoint community.

It may also be worth asking at Sharepoint Stack Exchange or other fora where someone may have shared something closer to what you are trying to achieve.

Is there a way for your script to display all the alerts from the person and to allow me to indicate yes or no regarding deleting of the alert? I have the old URL where the alert was originally created, if there is a way to filter the alerts examined so that one sees a lesser number of alerts.