There are a number of players after the fact of the Halloween event that have been using it or experiencing bugs because of it still being in Lumbridge. For example, I still had the occasion where I could complete the event two weeks after the release of the event. And there are reports of people getting stuck behind invisible barriers of the particular blocking element to originally keep a player isolated in the event until completion.
In light of these problems and gimme ability from keeping the event still there, I'd advise that now two weeks after Halloween passes for it to be removed and keep new and existing players from going through some of the bugs this event still causes with its availability in-game.