Tips on Customizing Writer Helper

How to Hide Writer Helper Admin Menus

function plt_hide_writer_helper_menus() {
	//Hide "Writer Helper".
	remove_menu_page('wtr_helper');
	//Hide "Writer Helper → Starting with WH".
	remove_submenu_page('wtr_helper', 'wtr_helper');
	//Hide "Writer Helper → My Books".
	remove_submenu_page('wtr_helper', 'wtrh_books');
	//Hide "Writer Helper → Bookworlds".
	remove_submenu_page('wtr_helper', 'wtrh_bookworlds');
	//Hide "Writer Helper → My To Do List".
	remove_submenu_page('wtr_helper', 'wtrh_todolist');
	//Hide "Writer Helper → Statistics".
	remove_submenu_page('wtr_helper', 'wtrh_stats');
	//Hide "Writer Helper → Users".
	remove_submenu_page('wtr_helper', 'wtrh_users');
	//Hide "Writer Helper → Communities".
	remove_submenu_page('wtr_helper', 'wtrh_communities');
	//Hide "Writer Helper → Settings".
	remove_submenu_page('wtr_helper', 'wtrh_settings');
}

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

Where do I put this code?

How to Hide the "Writer Helper - Statistics" Dashboard Widget

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

	//Remove the "Writer Helper - Statistics" widget.
	remove_meta_box('wtrh_stat_author_dashboard_widget', 'dashboard', 'normal');
}

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