Thank you for using Sling Community. I can definitely understand how this can be confusing and frustrating. There is a default Administrative password, and it is admin. However if this does not work for you, the way around it is resetting your Slingbox back to its factory settings, and then setting it up again. I have provided you with the article below on how to do so.
I hope I was able to help!
Sling Media Moderation Team