Stop displaying Permalink

You could only hide this box with additional CSS in the backend. There are 2 possibilities for this, which you could insert in the functions.php of your child theme, in a suitable code snippet plugin or your own plugin:

Variant 1: add the necessary CSS property to an already existing CSS file:

function my_admin_style() {
	wp_enqueue_style(
		'custom-style',
		get_template_directory_uri() . '/css/style.css'
	);
	$custom_css = '#edit-slug-box {
  display: none;
}';
     wp_add_inline_style( 'custom-style', $custom_css );
}
add_action('admin_enqueue_scripts', 'my_admin_style');

Variant 2: include only one CSS file and add the necessary CSS property to this file:

function my_admin_style_v2() {
	wp_enqueue_style(
		'custom-style',
		get_template_directory_uri() . '/css/style.css'
	);
}
add_action('admin_enqueue_scripts', 'my_admin_style_v2');

Add to style.css:

#edit-slug-box {
  display: none;
}