What should a person do regarding money he earned from impersonating a girl on social media and sending pornographic images in exchange for money, and what should he do if he does not possess sufficient funds to return it?

If the earning is illicit from someone who paid willingly and received their forbidden compensation, it should not be returned to them. Instead, the earner must repent from it and dispose of it by spending it on charitable causes. Alternatively, if the earner or those whose maintenance is obligatory upon him are in need, he may take from it what suffices their need. Or, he may take from it if he is proficient in trade or craftsmanship.