AITAH for not deleting photos of my brother before he transitioned?

My brother is trans and I still have a bunch of childhood photos from when we younger and before he transitioned. He got really mad at me, saying that I have to delete them. I am hesitating to as they are important memories for me. I’m not that educated on being trans and I don’t want to be offending anyone. I haven’t shared the photos or anything, is it okay for me to keep them?