How to remove melted crayon from exterior stucco?

You could try a blowdryer or an iron

Try a steamer, but have someone ready with a cloth to wipe off the wax as it melts so it doesn't run and make a bigger mess.

Yes, some form of heat. Get as much wiped off as you can. Then use a really good degreaser - even Dawn dish soap will probably work.

Try putting old rags on the stucco and use an iron to melt the crayon onto them. The wax should lift off onto the rags.

Paper towel over crayon and a blow dryer to soak up crayon. Then a good scrubbing.

You can always use a hair dryer. Once the crayon is melted blot it with newspaper or paper towels.

is it in a suny area? You used iron with a cloth over it to absorb the melting crayon. Or get those kiddies out there with some ice cubes and see if you can make it cold enough to crack off (like you do with chewing gum in hair). Try ice first, it will be less of a mess.