Even if United do not have grounds for termination, they can suspend him. EtH has set out clear rules and guidelines for every player.
Ronaldo has come out and said, he wont play for 3 mins, well he is under contract at United as a player, he does what the manager tells him.
EtH should tell the board, its him or Ronaldo, he does not want him anywhere near the first team squad.
Go to the teams that wanted you, that will pay you. If none come in for him in Jan, he rots training alone not even with reserves because he isnt really a good role model.
People think Ronaldo, the utter professional, but clearly he isn't.