elabits

From here I can access toothdocsd.com/wp-admin (or toothdocsd.com/wp-login.php) normaly.

Have you solved the problem?

Regards.

Have a look at your installed plugins, probably you can identify it reading the descriptions.

Regards.

You can remove this feature editing the content-single.php file, located at the main directory from your theme.

Remember that all changes will be overwritten when you update the theme to a new version. A good option to avoid this is to create a Child Theme, Child Themes are the recommended way of modifying an existing theme. More information can be found at: https://codex.ww.wp.xz.cn/Child_Themes

How to remove featured image background from Tesseract Theme single posts:

1.- First of all make a copy from the original content-single.php file.

2.- Edit content-single.php with a plain text editor.

3.- If the original file is like this:
( Source: github.com/Conutant/TESSERACT/blob/Master_Branch/content-single.php )

<?php
/**
 * @package Tesseract
 */
?>

<article id="post-<?php the_ID(); ?>" <?php post_class(); ?>>

	<?php if ( has_post_thumbnail() && 'post' == get_post_type() ) {
        $thumbnail = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'tesseract-large' ); ?>
        <div class="entry-background" style="background-image: url(<?php echo esc_url( $thumbnail[0] ); ?>)">
            <header class="entry-header">
                <?php the_title( '<h1 class="entry-title">', '</h1>' ); ?>
            </header><!-- .entry-header -->
        </div><!-- .entry-background -->

    <?php } else { ?>
        <header class="entry-header">
            <?php the_title( '<h1 class="entry-title">', '</h1>' ); ?>
        </header><!-- .entry-header -->
    <?php } ?>

	<div class="entry-content">
        <div class="entry-meta">
	        <?php tesseract_posted_on(); ?>
		</div><!-- .entry-meta -->
		<?php the_content(); ?>
		<?php
			wp_link_pages( array(
				'before' => '<div class="page-links">' . __( 'Pages:', 'tesseract' ),
				'after'  => '</div>',
			) );
		?>
	</div><!-- .entry-content -->

</article><!-- #post-## -->

4.- To remove the featured image background, change it to this:

<?php
/**
 * @package Tesseract
 */
?>

<article id="post-<?php the_ID(); ?>" <?php post_class(); ?>>

        <header class="entry-header">
            <?php the_title( '<h1 class="entry-title">', '</h1>' ); ?>
        </header><!-- .entry-header -->

	<div class="entry-content">
        <div class="entry-meta">
	        <?php tesseract_posted_on(); ?>
		</div><!-- .entry-meta -->
		<?php the_content(); ?>
		<?php
			wp_link_pages( array(
				'before' => '<div class="page-links">' . __( 'Pages:', 'tesseract' ),
				'after'  => '</div>',
			) );
		?>
	</div><!-- .entry-content -->

</article><!-- #post-## -->

5.- Test it and let me know if you have any problem.

Regards.

Set the main language to Danish.
For the backend you can use a plugin like “English WordPress Admin”:
https://ww.wp.xz.cn/plugins/english-wp-admin/

Regards.