Wait for the oven to completely cool. Do not try to remove baked-on aluminum foil while the foil or oven are still hot.
Fill a bucket with warm water. Add enough liquid dish soap to create suds. Dip a two-sided sponge into the bucket and agitate the water until the soap is completely incorporated.
Scrape up as much of the aluminum foil as possible with a plastic kitchen spatula. Do not use a metal spatula or you may scratch the enamel finish of the oven.
Wring the sponge out over the remaining spots of aluminum foil. Let the soapy water sit for five minutes. Scrub the spots of aluminum foil with the rough side of the two-sided sponge. Continue until the soap loosens the foil and the foil comes up.
Wipe out the inside of the oven with a dry towel to remove the soapy water.