You can't erase history.    Further, if you start to apply modern standards to every person throughout history - you'll have to erase a lot.    Eg:  What about William Lyon MacKenzie King?     Well documented for allowing his anti-semitic views to influence immigration policies.    Sanctioned the internment of Canadians of Japanese descent and compounded it with the unlawful seizure and sale of their property to pay for their own incarceration (and the internment didn't end until 1949 - four years AFTER the war ended).    Yet he was elected as PM and served until 1948.    So does that mean the electorate of the time should be held responsible too?

So where does it end?     

Rather than remove names and/or monuments - I think it's better to put up additional monuments/plaques which offer a modern interpretation of their legacies good and bad.   An important historical perspective is that these politicians (and monuments) were once popular - which is illuminating about the times.