Post to facebook intro image showing.

I have the Social theme. It has the intro page image. When I publish a post or page to facebook this image is included in the facebook post. I am not wanting this. Is this a bug, or is there a way to disable this?

Here is the screenshot to the social theme intro page
https://nimbus.everhelper.me/client/notes/share/16793/pMUUI4qb07hA3z3AcXntqnchqueoHoFz/

Here is the screenshot of the post before I publish it in dashboard.
https://nimbus.everhelper.me/client/notes/share/16795/iC98Wl7SsUHfglLOqe2KwJzcL3OxsRpD/

Here is the screenshot of what it looks like in Facebook
https://nimbus.everhelper.me/client/notes/share/16796/2uL3gKC4zovOfrsTKAJonJQda0BMT8Fk/

It was already suggested that I add this code to the functions.php file.

To make sure Facebook picks the correct items for the shared post, we need to add meta tags. Kindly paste the following code in your themes functions.php file

'// Facebook Open Graph
add_action('wp_head', 'wpmu_theme_add_fb_open_graph_tags');
function wpmu_theme_add_fb_open_graph_tags() {
if (is_single()) {
global $post;
if(get_the_post_thumbnail($post->ID, 'thumbnail')) {
$thumbnail_id = get_post_thumbnail_id($post->ID);
$thumbnail_object = get_post($thumbnail_id);
$image = $thumbnail_object->guid;
} else {
$image = ''; // Change this to the URL of the logo you want beside your links shown on Facebook
}
//$description = get_bloginfo('description');
$description = wpmu_theme_custom_my_excerpt( $post->post_content, $post->post_excerpt );
$description = strip_tags($description);
$description = str_replace(""", "'", $description);
?>
<meta property="og:title" content="<?php the_title(); ?>" />
<meta property="og:type" content="article" />
<meta property="og:image" content="<?php echo $image; ?>" />
<meta property="og:url" content="<?php the_permalink(); ?>" />
<meta property="og:description" content="<?php echo $description ?>" />
<meta property="og:site_name" content="<?php echo get_bloginfo('name'); ?>" />

<?php }
}

function wpmu_theme_custom_my_excerpt($text, $excerpt){

if ($excerpt) return $excerpt;

$text = strip_shortcodes( $text );

$text = apply_filters('the_content', $text);
$text = str_replace(']]>', ']]>', $text);
$text = strip_tags($text);
$excerpt_length = apply_filters('excerpt_length', 55);
$excerpt_more = apply_filters('excerpt_more', ' ' . '[...]');
$words = preg_split("/[n
]+/", $text, $excerpt_length + 1, PREG_SPLIT_NO_EMPTY);
if ( count($words) > $excerpt_length ) {
array_pop($words);
$text = implode(' ', $words);
$text = $text . $excerpt_more;
} else {
$text = implode(' ', $words);
}

return apply_filters('wp_trim_excerpt', $text, $raw_excerpt);
}'

I added that code to the end of the functions.php file but it did not solve the issue. It is not a facebook caching issue as I have changed the image and the new image will display in the post as well.

Thank you in advance for getting rid of this image posting problem.