How to Hide DarkLooks - Dark Mode Switcher For WordPress Admin Menus

function plt_hide_darklooks_dark_mode_switcher_menus() {
	//Hide the "DarkLooks" menu.
	remove_menu_page('darklooks-setting-admin');
	//Hide the "DarkLooks → Settings" menu.
	remove_submenu_page('darklooks-setting-admin', 'darklooks-setting-admin');
	//Hide the "DarkLooks → Recommended Plugins" menu.
	remove_submenu_page('darklooks-setting-admin', 'darklooks-recommended-plugin');
}

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

Where do I put this code?