Tips on Customizing Simple History

How to Hide Simple History Admin Menus

function plt_hide_simple_history_menus() {
	//Hide the "Dashboard → Simple History" menu.
	remove_submenu_page('index.php', 'simple_history_page');
	//Hide the "Settings → Simple History" menu.
	remove_submenu_page('options-general.php', 'simple_history_settings_menu_slug');
}

add_action('admin_menu', 'plt_hide_simple_history_menus', 51);

Where do I put this code?

How to Hide the "Simple History" Dashboard Widget

function plt_hide_simple_history_dashboard_widgets() {
	$screen = get_current_screen();
	if ( !$screen ) {
		return;
	}

	//Remove the "Simple History" widget.
	remove_meta_box('simple_history_dashboard_widget', 'dashboard', 'normal');
}

add_action('wp_dashboard_setup', 'plt_hide_simple_history_dashboard_widgets', 20);