Attempting to add another website to account

I cannot get our main site added to this account. It continues to ask for an old sites username and passwd which no longer exits. The files are no longer on the FTP and there is no way to get an email of a new passwd or anything. The website I need to add is Ive tried deleting the plugin after deactivating it and then a re-install to no avail. It continuously looks for the old account.