I think if the U.S. had any influence in Pakistan, they would have used it before 2021 to stop the incessant support by Pakistan for the Taliban in Afghanistan. And they would have also used it to have Pakistan hand over bin Laden who was being sheltered in Abbotabad, within walking distance of a Pakistani military academy. If the U.S. government got zero cooperation from the Pakistani government in those areas, I doubt they have the influence to get rid of the prime minister over some insignificant matter like whatever Khan did.