I changed the state of a TFS task I was working on recently, only to discover the workflow wouldn’t let me return it to it’s prior state. Until today, I didn’t know it was possible to delete TFS tasks if you made a mistake in changing one. But some Googling revealed a blog post that explained how to delete tasks.
The direction of the slashes for the URL can point forward (/) instead of backward () and the witadmin.exe destroywi /Collection:<TFS url> /id:<Task id> command still works.