It's just not celebrating people who are seen as controversial.
People can still learn about these people in books.
In films
At school.
It's just that they aren't being celebrated by having public recognition and the honour of a statue or a street name.
I would link to a story - but there would be so many of them as the Government (and certain media organisations) seem to think that it's a war on our history.
I guess a lot of it is down to the person being celebrated. And whether that celebration is still deemed 'worthy' 100s of years later.
Statues have been removed in the past for a range of reasons. I wonder how many of the Victorian statues will still be up in 200 years time?