By default we have always sent any email notifications about account creation requests or privilege requests to ALL administrators.
Administrators can now decide who should receive these notifications from
Settings > Security > Account / Privilege Request Notifications.
Leave the setting in the default "All site administrators" to continue to send notification emails to all administrators.
Change the setting to "Selected site administrators only" and add administrator users to send to the selected administrators only.
You can also leave this box blank and the request notifications will not be sent to anyone.