While oil is heating, lay out as many wrappers as you plan to use. Have a small bowl of water nearby to wet your fingers. Put a small dab of cream cheese in one corner of each wrapper, about 1/2” from the edges. Use about 2 tsp. for egg roll wrappers or 1 tsp. for wonton wrappers. Using your fingers, wet the two edges nearest the cream cheese, then fold the other half down and seal the edges, making a triangle shape. Seal the edges tightly, but try to leave small gaps at the corners so the triangles will not expand so much that they burst.
Drop several wontons into oil at a time. Turn over when the edges start to brown and cook for another minute or two. Set on paper towels to drain, then serve hot with sweet-and-sour sauce.