How to Hide JumpLinks Flow - Editorial Review & Content Approval Workflow Admin Menus

function plt_hide_jumplinks_editorial_workflow_menus() {
	//Hide the "Settings → Flow" menu.
	remove_submenu_page('options-general.php', 'jumplinks-editorial-workflow');
}

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

Where do I put this code?