In on premises deployments, your network administrator would create and delete user accounts. The Dynamics 365 admin would then assign permissions to users in Dynamics 365.
This post explains three administrator roles:
Office 365 Global AdministratorDynamics 365 System AdministratorDynamics 365 Service Administrator
You may think that the Dynamics 365 system administrator would have power to do all the actions needed to manage Dynamics 365, but this is not the case. What's different in Microsoft cloud deployments is that licenses and user accounts are managed in Office 365 by an Office 365 Global Administrator. This role is analogous to a network administrator for an on premises deployment. The Global Administrator is the only …