Gutenberg remove Most Used group

Add CSS to wp-admin:

functions.php:

function admin_scripts() {
  wp_enqueue_style('admin-edits', get_stylesheet_directory_uri() . '/assets/css/admin.css');
}

add_action('admin_enqueue_scripts', 'admin_scripts');

admin.css:

#block-editor-inserter__search-1:placeholder-shown + .editor-inserter__results .components-panel__body:first-of-type {
  display: none;
}