Tips on Customizing WordPress Flipbook by Supsystic

How to Hide WordPress Flipbook by Supsystic Admin Menus

function plt_hide_digital_publications_by_supsystic_menus() {
	//Hide "WordPress Flipbook by Supsystic".
	remove_menu_page('digital-publications-supsystic');
	//Hide "WordPress Flipbook by Supsystic → WordPress Flipbook by Supsystic".
	remove_submenu_page('digital-publications-supsystic', 'digital-publications-supsystic');
	//Hide "WordPress Flipbook by Supsystic → Overview".
	remove_submenu_page('digital-publications-supsystic', 'admin.php?page=digital-publications-supsystic&tab=overview');
	//Hide "WordPress Flipbook by Supsystic → Publications".
	remove_submenu_page('digital-publications-supsystic', 'edit-tags.php?taxonomy=dps_book');
	//Hide "WordPress Flipbook by Supsystic → Pages".
	remove_submenu_page('digital-publications-supsystic', 'edit.php?post_type=dps_page');
}

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

Where do I put this code?

How to Hide the "Batch add pages" Meta Box

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

	//Hide the "Batch add pages" meta box.
	remove_meta_box('dpsBatchAddButtons', $screen->id, 'side');
}

add_action('add_meta_boxes', 'plt_hide_digital_publications_by_supsystic_metaboxes', 20);