For when the last admin or CEO cannot sign in. Everyone else is reset from Users & Roles.
An administrator can enable it under System Settings → Outgoing Email. Until then, use the server-file route below, or ask another admin to reset your password from Users & Roles.
If another admin or CEO can still sign in, stop here — ask them to reset your password from Users & Roles. It is quicker and leaves this route unused.
Otherwise this writes a one-time code into a file on the server that only someone with cPanel or FTP access can read. That is how it confirms the request is really from you. Administrators and CEOs only.