When a relationship ends badly, it's only natural that we want to remove as many traces of our ex-partner from our life as possible. We delete their number from our phone, we throw out any possessions that remind us of them, and we'll either throw away or delete any pictures of them and us together. This girl must have been particularly attached to this photo, though. She still wants it; she just doesn't want him to be in it.
How she expected Fridman to be able to remove him without it looking obvious is anyone's guess, but he's managed to totally eliminate the boy without leaving any trace. She crucially forgot to tell him that she also wanted his clothes removed, though, so they stuck around. It may not be what she wanted, but at least now she can tell her friends she once went on vacation with the invisible man.