You can telnet into the unit's IP address to reset the password.  Here's how to do it with PuTTY:

 -- open a telnet session to the 532's IP address;

 -- at the Please Log In prompt:

   Username: knockknock

   Password: whosthere

 -- type the command

clear_pw 

and hit enter;

 -- the hardware should respond with Password Cleared.

That's it. The only remaining place for a password is in the GUI itself and it has no effect for remote logins.