I'll add what I just learned today. I had accidently got Heat 'n Bond Lite fusible onto the top-side of my applique background and paniced out. I asked this board for help and several came to my rescue. The first suggestion I tried worked.
I put my iron on scorching hot with steam on...held slightly above the spot and shot it with the steam for a few seconds. Then I quickly applied a cloth to the top and steam-ironed back and forth several times shooting the steam. I did the same thing 3 times and by the third time it was all gone.
Needless to say I am very grateful to those that tried to help me and especially to the one that thought of doing it this way.
Hope this helps if you are every as careless as I was.