Whilst we should have gotten rid of him a few weeks ago when the news broke, it's still not too late. Should never ever have brought him back in the first place.....nice one Fergie.
However I don't think you can cancel contracts if a player has an attitude issue, see Martial, Winston Bogarte and many others for example. Unless of course it's a mutual cancellation, then it's not exactly a threat.
Would be funny if it was mutually cancelled and he was without a club until January when some chinese club offer him a contract.