Do you think it’s important preserve or destroy bad parts of history?

Preserve.

Good or bad is irrelevant as ideas and attitudes shift like fads, albeit more slowly. Haphazardly removing things you find unpleasant is sure to remove things that were good. It's just like clipping pages out of the book. If you clip the villain out, readers will never grasp the full significance of what the protagonist achieved.

Also, history doctoring is a propaganda tool and it's favored by Communists. Communism is a hateful ideology. Tens of millions of its own people have been slaughtered in its name.

I think it's important to keep them.

But it's also important to speak the truth of the historical narrative.

If you want to keep a statue of the Confederate general Nathan Bedford Forrest because it is a historical monument-- legit. But tell the truth at the same time. He was a war criminal.

Preserve as weird as that sounds. I've been to a Ripley's museum and viewed torture devices from the medieval era, "iron maidens" and other devices. Only saw them in books and seeing crap like that up close in a collection makes you understand what was going on better...brings history to life in a way.

Everything should be kept

History can’t be changed , only lied about

Why is Hitler's piano considered a part of history? I mean, it's just a piano, it's Hitler's and it's not like he was a famous musician anyway but even if he was, it's still just a piano.

Preserving in some way is important, lest we forget. If there is a debate about how it should be preserved then let's all have that debate with no holds barred until we reach a consensus.

Preserve.

The objects can go...it's the truth that shouldn't change

No mementos or knowledge of history should ever be destroyed.
Just look at the travesty that happened in China during the cultural revolution?
Untold numbers of art, architecture, and antiques forever lost because of a time it represented. Tragic and shameful.