A collage/university in the UK (unfortunately can't remember which one) dealt with a similar problem well. It had statues of the founders out front. Unfortunately, they made their money from the slave trade. There were calls to destroy the statues. They instead, moved them to a small, half forgot garden in the back. As well as their original descriptive plagues, some more were added, explaining how they made their fortunes, and the various moral failings we now see in them.

It seems to me like this struck a good balance. It acknowledged the good they did, while emphasising the bad. Failing to recognise both good and bad can occur in individuals is often how history can repeat itself.

In short, don't destroy them. Instead, stick them at the back of a museum to the horrors of slavery, half forgotten, except for their crimes.