I use a product called Iron-Off when I goof up and get fusible stuck on the bottom of my iron or starch. I keep it wrapped in an old rag and add the product onto this rag and then rotate my hot iron over it till it all comes off. Sometimes it might take a couple shots of it, especially when its totally covered with gunk. But it works. I got mine at Walmart.

Ive used Hot Iron cleaner in tube. Get the big tube near laundry aisle in WM. Have also used a damp Magic Eraser successfully. Recently read about using cheap white paste toothpaste. Haven't tried it, but I imagine it would work well.