[Clearing User Name field history lists?]

Hello?  Does anyone know how to do this?

[Clearing User Name field history lists?]

Hi,

I have a couple web sites where I made mistakes and inadvertently typed passwords in username field.  So now the password can be seen when the username field auto populates it history.

How do I clear the list of usernames from that site?  I don't want to clear ALL username list from ALL sites, can I do just certain ones?

Thanks,

MP