If you don’t like the reminders to repurchase items, you can turn that off in the Echo Settings. On the Echos with a screen, it's on the “Home Content” page. Towards the bottom of that page is an item that says “You might be running low on...” and you can turn that on or off. Once I turned it off, I stopped getting those types of messages. (I'm not sure how this works with the non-screen Echoes - it's probably somewhere in the Alexa app.)
I love walnuts, but usually get mine from Nuts.com. I like Trader Joe's walnuts too. What brand are you buying from Amazon?
And to Don, the original poster - I have Prime myself, but I also hate that type of thing being forced on me. I'm glad you discovered how to avoid it, and I'll keep that method in mind if I run into this sort of thing in the future.