For Blog pages, your blog posts are always ordered by the Publish Date set for the blog post. While you still need to set this in order to properly order your blog posts, you can choose to hide this date when viewing your blog page and individual blog posts.
Navigate to the Page Settings for your blog page:
Scroll down until you see the section titled “Blog Feed”. You’ll see an option titled “Display Post Date?”
When setting this to “No” all of your blog posts associated to this Blog will not display the Publish Date on both the blog feed and the blog post itself: