To resolve this issue, grant the Administrator role to another user or group before attempting to remove the local Administrators group from the vCenter Server Administrator role.
To grant the Administrator role to another user or group:
- On the vCenter Server, go to the Permissions tab, right-click and click Add Permission.
- Click Add and click on a user or group.
- Under Assigned Role, select Administrator from the dropdown menu.
- Ensure that Propagate to Child Objects is selected and click OK.
You can now remove the local Administrators group from the vCenter Server Administrator role.