FTP Password

I have a FTP server setup on my Windows2000 that prompts users for their username and password to get to their files. On a Windows XP workstation using IE6 a user clicked the “Remember Password” check box and now they can’t type in another username and password. Does anyone know where this is stored so I can delete it. I’ve tried deleting cookies and “Clearing Passwords” under the Autocomplete option in IE.