Go to Administration ⇒ Settingsand click on Companies.
The name of your Root company will be the same as the name of your Tenant.
New subcompanies can be added by clicking + .
Subcompanies can be edited. They can also be deleted but only in the case if no user is assigned to that subcompany. You can also create a child of a subcompany by clicking the + icon.
Every subcompany will have a black house icon next to the name, but subcompanies within subcompanies will have a white house icon.
All roles in the subcompany, whether they are predefined, or custom will be able to work only in their subcompanies and will not have access to the other subcompanies, that are located higher in the hierarchy.
Info
Admin is the only role that can create companies and structure them in a desired order