"Administrator" is just a role with a pre-existing set of permissions on a project area.  If you delete the role you are free to create another role with any set of permissions you would like an administrator to have.  Deleting the administrator role on a project will just mean there are no users with permissions to perform administrative tasks in that particular project area.  This would be more of a problem if you were able to delete the server admin capability (ie - a JazzAdmin), but for a project area I don't see it being a big concern since the role could be re-created or re-defined by anyone with JazzAdmin permissions.

Hope it helps,