I've tried just about everything everyone suggested & so far no luck. I have it soaking in vinegar water right now.
I was really hoping the Blue Line Eraser would work. Tried it several times again & no luck with that either. It looks like I'm stuck with it. Lesson learned. Do NOT iron before removing blue lines!!
>>Is it the outside corner? if so I would remove that corner square and pop either the same design back in or something different