If you are using a Standard Xtreme Page with posts for your blog page, just open the page editing page, and in the Xtreme 4 Options for this page you have an option to hide the header image. You can also replace the header image by another one if you like.
But if you use the WordPress default blog page you would not have this option.
To make sure you are NOT using the WordPress default blog page, go to Settings > Reading. Have the front page set as a static page, and make sure nothing is selected in the Post page drop down list (showing -select-)
Then your blog page can be created with a regular page, select the “page with Posts” template for it, and publish, and you will have ALL the weaver Xtreme options available