If you didn't change the default password from your Pocket WiFi device, you can do this only if you are connected to its network. From your Internet browser, go to the following address :
http://192.168.0.1. After you see the default page, enter in the upper right corner of the screen the default password which is admin. After you connected to the device, go under WiFi > Security. There, you should be able to find an option that you can use to change the fault password.