// Hide the first image from WordPress post content
function hide_first_image_from_post_content($content) {
    // Check if we are on a single post page
    if (is_single()) {
        // Find the first image in the post content
        preg_match('/<img.*?>/', $content, $matches);
        if (!empty($matches)) {
            // Replace the first image with an empty string to hide it
            $content = str_replace($matches[0], '', $content);
        }
    }
    return $content;
}
add_filter('the_content', 'hide_first_image_from_post_content');