How to Hide the "Simple Editor Control" Admin Menu

function plt_hide_simple_editor_control_menus() {
	//Hide the "Tools → Simple Editor Control" menu.
	remove_submenu_page('tools.php', 'simple-editor-control');
}

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

Where do I put this code?