How to Delegate SharePoint Online Administration Tasks
With Office 365 and SharePoint Online specifically, you can delegate administration up and down. By delegating administration and sharing the workload, you can empower the person who knows his business unit best to control who gets access, how much storage to have, and what custom solutions to install in his site collection.
At the top level, the Tenant Administration level, Office 365 enterprise plans offer the following administrator roles in the Microsoft Online Administration Center:
Global Administrator: This role is the top-level administrator for your company who has access to all the features in the administration center. Global administrators can assign other administrator roles, including granting someone a global administrator role.
Password Administrator: This role can reset passwords for users and other password administrators, manages service requests, and monitors service health.
Service Administrator: This role is limited to managing service requests and monitoring service health.
User Management Administrator: This role can do everything password and service administrators are empowered to do plus the ability to manage user accounts and user groups. The exception is that this role cannot create or delete other administrators or reset passwords for billing, global, and service administrators.
Billing Administrator: This role is limited to making purchases, managing subscriptions, support tickets, and service health.
From the Microsoft Online Administration Center, the Global Administrator can go down one more layer to the SharePoint Online Administration Center where further tasks can be delegated. The SharePoint Online Administration Center is where site collection administrators are assigned, who in turn can go down one more layer to assign site collection owners.