Can I Create a Sub-User Under a Main User's Account?

I am the Main User on a Cyber Panel account that has several websites under it. How can I create a new user account (like a sub-user) under this same account of mine and give this sub-user access to one specific website within the Main User’s account?

Follow-up +

A resaler and admin can create a sub-user. But it is not possible to add users under user.