Messages syncing between iPhone and Apple Watch

How do I stop messages from going to my Apple Watch and taking up storage? I turned off notifications. How can delete messages from Apple Watch without deleting it off of my iPhone? I read if you delete off watch it should not delete off phone but that is not the case as I tried and it deleted the message off my phone as well. I have an iPhone 15 pro max on iOS 18.5 and an Apple Watch 8 on watchOS 11.5

[Re-Titled by Moderator]

Original Title: Messages on Apple Watch