You can't just go out there and delete history, no matter how bad it was, because you know what happens when you do that? You will end up repeating the past mistakes. The book shows how society was back then, you can't just all of a sudden decide that it didn't exist and somehow put kids in a bubble and hide our past from them.
It isn't about deleting history, it's about not teaching the same thing as was taught in the past. Normalisation of the depiction of racist serotypes in books & media normalises racism. It's subtle but in conversations I've had with PoC, they point out all these subtlies that they notice but were an invisible part of my conditioning growing up.
The history still exists, for when it's appropriate to study the history of race relations, but if you're teaching pre-school & primary school children to read you don't need to do so with images of black people dressed as tribesmen which normalise racist depictions of those people.
