A MTG rules arguement I had with friend about Grip of Amnesia (Judgment):Who's right?

This came up in a Magic: The Gathering game I played today with a friend:

It is regarding Grip of Amnesia from Judgment. That card says:

Counter target spell unless its controller removes his or her graveyard from the game. Draw a card.

So I play this card in the beginning when my friend still doesn't have anything in his graveyard. Because if he doesn't have anything in his graveyard, how can he remove it? But he didn't agree and said that he can remove his graveyard even if it is empty.

In the end we flipped a coin and he won so I did not counter the spell.

Who was right me or him?

Your friend was right.

The FAQ from Wizards of the Coast specifically states that You can choose to remove your graveyard from the game even if there are no cards in it.