I would take scraps of muslin and iron over them and while they're still hot, peel the muslin off. Keep doing that until it's almost gone.
Take the cover off the ironing board and saturate the areas with Goo Gone, let it sit for an hour or so, then spray it with aerosol Shout and wash it in hot water.
Then while it's drying, go hem some squares of muslin so that you can use fusibles and heavy starch on your ironing board without gooing up your cover. ;)