How to Hide the "Block for Apple Maps" Admin Menu

function plt_hide_maps_block_apple_menus() {
	//Hide the "Settings → Block for Apple Maps" menu.
	remove_submenu_page('options-general.php', 'block-for-apple-maps');
}

add_action('admin_menu', 'plt_hide_maps_block_apple_menus', 21);

Where do I put this code?