The Azure Blockchain Workbench uses Azure Active Directory (Azure AD) for authentication, access control, and roles. Users in the Blockchain Workbench Azure AD tenant can authenticate and use Blockchain Workbench. Add users to the Administrator application role to interact and perform actions.
Blockchain Workbench users need to exist in the Azure AD tenant before you can assign them to applications and roles.
Once users have been added to the directory, you can assign administrator role. Users in the Administrator group are associated with the Administrator application role in Blockchain Workbench.
Please follow the documentation for more details to Manage Blockchain Workbench administrators.
Source: MSDN