I want to remove the gray “archive” on my blog page for posts.

I want to remove the gray “archive” on my blog page for posts. https://www.axumcreative.com/street-portraits-la-blog/ I specifically want to remove the gray box and even remove text that says “Archives”. I would really like to insert an image in this area as default blog page image. I just wanted to be specific and clear about what I am trying to do. Please advise.