I'd go for the 'You do not destroy books. You don't have to read them, you don't have to like them anymore, you don't have to agree with them or the writer, but you do not destroy books' approach.
Books are a tangible history of ideas and thoughts. Erasing those thoughts, no matter what they were, means deleting ideas about freedom, self determination, heroism, standing up for what is right - and of understanding the beliefs and motivations of people that do wrong and learning how to stop terrible things happening.
It's not about disliking one author, it's about understanding people. To erase HP books is to erase how the concept of racial purity being wrong was introduced to children, how people can be tricked by the media or with promises of wealth/power/superiority, how heroes aren't just big and strong and loved by all, how sacrifice can redeem somebody, how help can be found in the darkest times and how even being the winner carries a heavy cost.
'To destroy those books means it's also OK to destroy books of people you do agree with, to erase evidence of girls, of children, of people from different countries and places having intelligence, strength or deserving to exist. Which isn't right. You do not have to read them anymore. But you do not ever, ever destroy books'.