You can't do that as a seller if the football club owns the stadium. You don't have that power.I'm 99.9% sure that isn't true.
However, as sellers you could probably insist on Enic keeping the stadium and renting it to Spurs, as long as you found a buyer stupid enough to agree to those terms.
The football club would have to sell the stadium to ENIC. In theory, it can be done. It would have to be at FMV, otherwise raising a while bunch of investigations. And I don't see ENIC wanting to deal with that while putting down a billion dollars just to own the stadium.