You cannot exercise shares. You can exercise options. But If I'm not mistaken, at this point, even if he sold all his GME stock, he wouldn't raise enough money to exercise all of his option contracts. I could be wrong.
He is a smart cookie, "Zip Trader". Roaring Kitty could roll over his options to a higher strike price for July when the May FTD T+35 is due. I understand that Roaring Kitty is an expert Options/Stock trader; he was Licensed for stocks and options. People criticize him and state he doesn't have the money to exercise the 120.000 Call options at a strike of $20.00, but I would bet money that he has a Master Plan.