I used Admin Menu Editor Pro.
When adding menus using the Admin Menu Editor Pro, you must check WP ERP capabilities given in erp/modules/hrm/includes/admin/class-menu.php and apply the needed capabilities. So you basically just get the URL of the menu, add the capabilities and that’s it. And use simple css to hide the top area menu if you want to hide the default WP ERP top area menu…
If you want to take things further, you can use plugins like Clientside to make things really pretty. I’ve done the project while ago and delivered it with lots of customization, even WP experts in the company didn’t know it was WordPress.
Good luck. Hope I helped.