You can kill a man, but you cannot kill an idea.
You can kill a million men, and a god, and a state, and all hope, and then you can kinda maybe kill an idea.
You can burn down shrines and libraries like a pack of barbarians while calling yourselves the defenders of Law. You can wreck all printing presses which print materials you can trace. You can punish people for not just dissenting but merely not noticing and reporting dissent. You can read the thoughts of everyone who looks like they might ever think something true. You can steal all the promising kids away to schools that do the opposite of education (Education: acquisition of knowledge and skills that are useful relatively to the goals of the educated person and their peers). You can perverse every school, every archive, every library, every port and stable, every temple and shrine, every workshop and manufactory, every notary office and town hall and marketplace and money itself and law itself and family itself against the causes that they were called from the void to defend.
And then you can mostly kill an idea.