What is the correct action to take regarding insane people who are bothered by boys, and thus curse Allah and the religion, and utter profanities and insults, knowing that it is impermissible to kill them?

The action involves restraining children and preventing them from harassing the insane. If disciplining and punishing the insane proves effective in deterring and restraining them, then they should be disciplined. Ibn Taymiyyah said: "The non-accountable person—such as a discerning child—is to be punished for indecency with a severe ta'zeer (discretionary punishment), and similarly, the insane person is to be beaten for what he has done, so that he may be deterred." The punishment that involves killing or amputation is what is waived for the non-accountable person.