The ability to proxy your access to someone else is active in Production since an upgrade to 12.2.4 of EBS. It may also be available in some 12.1.3 environments where a ATG patch has been applied to backport it.
This is functionality that is not desirable and needs to be disabled.
Remediation can only be done by logging into SYSADMIN
On this page (above), press the “Policies” link. You will receive this page (below):
At the above page, press the trash can to “Remove” the “All Users” line.
Press the “Apply” button.
In case there is a need to reverse this change, this is how the configuration looked before deleting it: