Tips on Customizing Load HTML Files

How to Hide Load HTML Files Admin Menus

function plt_hide_load_html_files_menus() {
	//Hide "HTML files".
	remove_menu_page('edit.php?post_type=html_files');
	//Hide "HTML files → All HTML files".
	remove_submenu_page('edit.php?post_type=html_files', 'edit.php?post_type=html_files');
	//Hide "HTML files → Add New".
	remove_submenu_page('edit.php?post_type=html_files', 'post-new.php?post_type=html_files');
	//Hide "HTML files → HTML files Categories".
	remove_submenu_page('edit.php?post_type=html_files', 'edit-tags.php?taxonomy=html_files_category&post_type=html_files');
	//Hide "HTML files → Settings".
	remove_submenu_page('edit.php?post_type=html_files', 'load-html-files-settings');
}

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

Where do I put this code?

How to Hide the "HTML Editor" Meta Box

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

	//Hide the "HTML Editor" meta box.
	remove_meta_box('load_html_files_editor', $screen->id, 'normal');
}

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