The correct way to stimulate a kitten to defecate: Gently stimulate the kitten's anal area, mimicking the behavior of a mother cat licking the kitten's anus to stimulate defecation. Note that it is "gentle stimulation" to avoid excessive force that could cause injury.

Suitable position: Position the kitten's body in a position similar to when the mother cat is licking it. This helps the kitten relax and defecate smoothly.
Pay attention to their diet: Make sure the kittens get enough water and food, especially unweaned kittens. Make sure they get enough mother's milk, which helps soften their stool and promotes defecation.