It should be in C:\Users\<username>\AppData\Roaming\Neolane\NL_5 .
You can simply type %appdata% in the Run box and should land in Appdata/roaming folder . From there search for neolane and inside it the NL5 folder . there will be a file called nlclient_cnx.xml and several other .xml files. These XML files contain the Urls and cached preferences.
You can either delete all the .xml files or just rename the NL5 folder and then install the console and all the preferences would be gone.
To remove cached navigation data you may simply follow these steps :
close the console open the folder "C:\Users\<Windows Username>\AppData\Roaming\Neolane\NL_5" delete all the xml files except nlclient_cnx.xml and delete the "nlclient" sub-folder Then restart the console and you should not be able to view cached navigation details.
I couldn't find the folder that you've mentioned. I removed the folder in Program Files > Adobe > Adobe Campaign v6 and then cleared by %temp% folder and this got rid of the error that I was having with upgrading the client console to a newer version. But this still didn't delete the cached connection URL's and all that, I'm not too sure where that is being pulled through from.