Check this   

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.

Was the below highlighted option been used?

Hi - yes!  And now the workflow has been deleted, it's still there

Try this: go to list settings > workflow settings where you would see an option to remove a workflow.

Hi!  The workflow has already been removed...

Check this:   

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.

Check this: How to Write and Run Scripts in the Windows PowerShell ISE  

Looks like I don't have the admin rights to run PowerShell   thanks for all your help though!

Hi - I still have this issue and no powershell - does anyone have a solution that doesn't use powershell?