I haven't seen any evidence to suggest they've closed it, and have seen circumstantial evidence suggesting they have not. You don't spend money on ads saying "we no longer have a financial stake in this stock" unless you, you know, have a financial stake in this stock.
Considering this is a hedge fund, I just assume they're lying because, you know, it's a fucking hedge fund.
EDIT: People are claiming CNBC bought ads, not Melvin Capital. https://i.redd.it/8vxraurkcce61.png