The most likely way to have a third-party editor installed would be through the use of a plugin (or, less likely, through a theme).
It seems unlikely that WP-Juicebox would detect CKEditor or FCKeditor unless such an editor was being used. If you have tried any third-party editors in the past, then perhaps they have not been fully deactivated and uninstalled, resulting in some files begin left behind that WP-Juicebox is detecting.
If you have already checked your plugins and would like me to investigate further, then I would be happy to do so but I would need access to your WordPress installation and web server. If you are agreeable to this, then please let me know and I will send you an email address where you can forward your WordPress and FTP login details on to me. Thank you.