How to unset adminmenu completely?

I don’t think you can remove it globally, maybe with traversing the global $menu array.

But you can unset each individually:

add_action( 'admin_menu', 'Wps_remove_tools', 99 );
function Wps_remove_tools(){

remove_menu_page( 'index.php' );                     //dashboard
remove_menu_page( 'edit.php' );                      //posts
remove_menu_page( 'upload.php' );                    //media
remove_menu_page( 'link-manager.php' );              //links
remove_menu_page( 'edit.php?post_type=page' );       //page
remove_menu_page( 'edit-comments.php' );             //comments
remove_menu_page( 'themes.php' );                    //appearance
remove_menu_page( 'plugins.php' );                   //plugins
remove_menu_page( 'users.php' );                     //users
remove_menu_page( 'tools.php' );                     //tools
remove_menu_page( 'options-general.php' );           //settings

}