Is it permissible for the husband to retract his choice if he gave his wife the choice between divorce and something else, and is it permissible for him to retract the delegation if he delegated the divorce to his wife after the marriage contract?

When a man gives his wife the choice of divorce or delegates the power of divorce to her, this is considered an agency (wakala). If the wife does not exercise her right to divorce, he is permitted to retract this delegation, and the agency thus becomes void, because the principal (muwakkil) has the right to retract what he has delegated.