Allow the dryer to cool completely -- so the melted chocolate has a chance to harden.
Scrape off as much chocolate as possible, using a rubber spatula or old credit card.
Place two or three old towels in the dryer. Turn the dryer on warm, and let it run for about 10 minutes. The heat of the dryer melts the chocolate, and the towel removes much of the residue.
Combine three to four drops of liquid dish detergent or general-purpose household cleaner in a cup of warm water. Dip a rag in the sudsy mixture, and then use the rag to wipe the entire inside of the dryer.
Wipe the inside of the dryer with a damp rag to remove the soap.
Place a clean damp rag in the dryer. Turn the dryer on for about 10 minutes. The rag removes any last traces of chocolate that may remain.
Wipe the dryer with a paper towel or clean lint-free rag.