This will make it so NOBODY can buy the unit, which is good for if you want a hero removed after a certain player picks it; but not for removing each player's ability to create more than one hero.neutral building-remove unit-type from sale
Player - Make [U]UNIT NAME[/U] Available for training/construction by [U]PLAYER[/U]
Player - Limit training of Heroes to [U]1[/U] for [U]PLAYER[/U]