If you want good laws, burn those you have and make new ones.In fact, destroying knowledge is not a method of creating knowledge, let alone of creating superior knowledge.
Voltaire is Terrible
Oh, come on. How could you hate a man who wrote, "A witty saying proves nothing?"
I think you're taking the prima facie reading of this quotation to heart. It's clear that he was writing metaphorically, as he often did.
And how do laws represent accumulated knowledge? All they represent is accumulated opinion, which is subject to human fallibility.
If anything, he was rejecting the implicit veracity of tradition.
So our laws don't contain more knowledge of how to have a peaceful society than, say, ancient Roman laws?
Of course it's a metaphor. He doesn't mean burn them, he means throw them out, disregard them, ignore them, and start from scratch. Starting from scratch is exactly the wrong way to create good laws.