Mix all the cream cheese, crab meat, sugar, and salt in a bowl. Stir to blend well. Place about 1 tablespoon of the cream cheese filling in the middle of a wonton wrapper. Dab some water on the outer edges of the wonton wrapper and fold the two ends of the wrapper together. Fold the other two ends to make a tiny parcel pictured below. Pinch to seal tight and make sure that there is no leakage.
Heat up a pot of oil for deep-frying and fry the crab rangoon until golden brown. Dish out with a strainer or slotted spoon, draining the excess oil by laying the crab rangoon on a dish lined with paper towels. Let the crab rangoon cools down a bit before serving them with sweet and sour sauce.