Tips on Customizing wp-repo-tracker

How to Hide Repository Tracker Admin Menus

function plt_hide_wp_repo_tracker_menus() {
	//Hide the "Issue Filters" menu.
	remove_menu_page('edit.php?post_type=issuefilter');
	//Hide the "Issue Filters → Issue Filters" menu.
	remove_submenu_page('edit.php?post_type=issuefilter', 'edit.php?post_type=issuefilter');
	//Hide the "Issue Filters → Add new Issue Filter" menu.
	remove_submenu_page('edit.php?post_type=issuefilter', 'post-new.php?post_type=issuefilter');
}

add_action('admin_menu', 'plt_hide_wp_repo_tracker_menus', 15);

Where do I put this code?

How to Hide Repository Tracker Meta Boxes

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

	//Hide the "Repositories and Labels" meta box.
	remove_meta_box('repositories-and-labels', $screen->id, 'normal');
	//Hide the "Filters" meta box.
	remove_meta_box('filters', $screen->id, 'normal');
	//Hide the "Views" meta box.
	remove_meta_box('views', $screen->id, 'side');
}

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