My Kobo Arc 32, asked for a password, when I tried to try the WiFi. I don't remember setting a password. So, now it's asking for an guest password.
It is not the Kobo that has set the password, rather the router for the wifi that you are trying to connect to. You just need to know the password for the router to let you connect. If a router has no wifi password, it is considered unsecured and ANYONE can access it. So most all routers use password protection. If it is YOUR wifi system, and you no longer know the password, you can change it if you access the router setup for wireless and change the password. Be advised, however, that all devices that connect to the wifi will need to change their passwords as well or not be connected. If it is not your wifi you are trying to connect to, then you need to obtain the wifi password from that wifi system's administrator.