Can't delete completed tasks that were once sub-tasks
I saw this answer https://todoist.com/Support/showQuestion/3902/ so I know it's normal for completed sub-tasks not being deleted.
But I have various completed sub-tasks that I moved to another project and then made them tasks (instead of sub-tasks). Still, they don't disappear when I click the 'Delete the completed task' link. Seems like a bug to me.
Actually, I just want these completed taks out of my view. So deleting them may not the ideal solution, but I don't know what else I can do to make them disappear. These tasks seem to 'remember' they were sub-tasks once and keep behaving like that.