You can also call ESET Customer Care at 866-343-3738 (Option 2) or 619-630-2300 directly. They're open M-F 6am-6pm Pacific and should be able to help you uninstall ESET.
If the Uninstaller is requiring a password, it'd likely be one that was set up by you or may be the password used for your Windows Login. Either way, ESET offers an unlock tool
to unlock this password with the help of customer care. There's also a manual uninstaller tool
you can run in Safe Mode that should help as well.