Hi Mahesh,
We would like to let you know that currently your provided requirement is not feasible in the Menu component that’s why we have suggested to use context menu. And you mentioned that header will be removed for your case. So, you can create context menu and open it whenever you want by using the instance. Whenever you want the sub menu items you can create by using the context menu. Please check this and get back to us if you need further assistance on this.
Regards,
Saranya D