How to Hide Spawnster Admin Menus

function plt_hide_spawnster_ai_content_generator_menus() {
	//Hide "Spawnster".
	remove_menu_page('spawnster');
	//Hide "Spawnster → Spawnster".
	remove_submenu_page('spawnster', 'spawnster');
	//Hide "Spawnster → Build Wizard".
	remove_submenu_page('spawnster', 'admin.php?page=spawnster&view=setup-your-website&_wpnonce=b38d46a03e');
	//Hide "Spawnster → Settings".
	remove_submenu_page('spawnster', 'admin.php?page=spawnster&view=settings&_wpnonce=b38d46a03e');
}

add_action('admin_menu', 'plt_hide_spawnster_ai_content_generator_menus', 11);

Where do I put this code?