How to remove Google fonts from wp-admin (Roboto) added by core

This line is in source of /wp-admin/ code. I do not wish to have extra Google fonts in Wordpress admin area.

<link rel='stylesheet' id='prefix-style-css'  href='+Slab:700' type='text/css' media='all' />

How to remove it? I have tried unsuccessfully this:

function my_dequeue_styles() {
    wp_deregister_style('prefix-style');
}

add_action('wp_print_styles', 'my_dequeue_styles', 999);
add_action('admin_init', 'my_dequeue_styles', 999);
add_action( 'after_setup_theme', 'my_dequeue_styles',999 );