No one is asking for history to not be taught in schools - quite the opposite in fact. A lot of countries (not just the US, but the UK in particular) typically do a very poor job at teaching the topics from the side of history they were on the 'wrong' side of (slavery, colonialism, genocides). All that's being asked is to not glorify the mistakes of the past. There are no statues of Adolf Hitler in the streets of London or people driving around with swastikas on their cars/clothing not because we want to forget the events of WW2 but because that's not the way anyone learns about history. No educational or historical point is made by driving around the Confederate Flag on your car any more than driving around with a swastika is. It diminishes the history and significance of those events to treat those symbols as some sort of decoration to be adorned on any object you see fit.