Follow below steps:-
Log in to the vSphere Client.
On the vCenter entity root level, right-click and select Add Permission.
The Assign Permissions window appears.
Select Administrator from the Assigned Role drop-down menu.
This menu displays all the roles that are assigned to the object. When the role appears, the privileges contained in the role are listed in the section below the role title.
Select Propagate to Child Objects.
Click Add.
The Select Users and Groups window appears.
Select the domain where the user or group is located from the Domain drop-down menu.
Type a name in the Search box or select a name from the Name list.
Click Add.
The name is added to the Users or Groups list.
Repeat steps Step 6 through Step 8 to add additional users or groups.
Click OK.
To finish the task, click OK.