menu

system.admin:
  title: Administration
  route_name: system.admin
  weight: 9
  menu_name: admin
system.admin_content:

This article show you how config Drupal Bootstrap theme allow show dropdown menu when hover and clickable parent menu

First add this css to your theme css, usually is style.css

@media (min-width: 768px) {
  .dropdown:hover .dropdown-menu {
    display: block;
  }
}

Second, override theme_menu_link to remove data-toggle