Thanks! However, the workflow isn't running on any items and I have purged all completed and deleted versions of it. It only appears on the item menu.
Thanks - I was hoping for a resolution I could do myself. I don't quite understand the first resolution and am worried about deleting other workflows. We can't use Sharepoint Developer with the version of Sharepoint we are using. Do you know if the first solution is run as a web part, script editor?
The first solution is in PowerShell script which can be executed on Windows PowerSell. Let me share the PowerShell script executable file which you can run on the SharePoint server.
Extract the attachment to get RemoveOrphanedWorkflowFromItemMenu.ps1 file. Edit this file to enter the web URL and List Name, and run the file on SharePoint server in Windows PowerSell.