Replace slider with a full width header image

Have you tried having just 1 image in a custom slider ?

Here’s the documentation link

Tick the Full Width Slider checkbox in Customiz’it!>Front Page

If I have understood correctly, it is NOT possible to replace the slider with a single header image.
I will have to create a slider with one image in it to produce this kind of display.

Ah, didn’t grasp the image bit, but it’s still the best solution.

Hide the controls using this snippet

Of course is possible, and why you say replace?
Don’t show the slider and put your image after the header with the hook…
__after_header
something like this (in your child theme functions.php):

add_action('__after_header', 'my_after_header');
function my_after_header(){
// here you can do some check on the page you're displaying
// for example if you want the custom html showing just in home page:
    if ( ! tc__f('__is_home') )
        return;
    $html = //something here, like the code to print the image ;
    echo $html;
}

That’s it.