an applique pressing sheet is made to fuse your appliques to it, then you can build an applique with multiple pieces into one unit before removing it to attach to the background piece it is going on- the fusable should not leave any residue - you do have to allow the pieces to cool before removing them-
and other than maybe needing to wipe the sheet off with a dry paper towel or soft cloth once in a while it should not require any (cleaning) and certainly should not need hot soapy water.
are you sure that is what you used?
a teflon applique pressing sheet is not a pressing cloth- which you place over something you want to press to protect it from direct contact with an iron (keeps fabrics from getting shiny or scorched from the iron)
you may be able to contact the manufacturer of what ever you used and explain what has happened then ask what you can do about it...applique pressing sheets come with good instructions and tips/uses for using them. or if you bought it locally maybe you can go back to where you purchased it for help.