I called Comcast and tried to find out how to deactivate HBOGo without physically having the ATV but she didn't really understand that the ATV only gets authorized once and you don't need to keep putting in a password. She kept saying "but the HBO is connected to your cable box and your internet with Comcast". And I would say, "But I can watch HBO Go in the airport on THEIR wifi and that's not my house NOR my internet". Kind of the whole point of the "GO", huh? Then she told me to ask Apple how I would remotely erase the password and I told her it was a one-time activation, not a stored password. I said I didn't see why, if I created a connection on my end, they didn't have a way to break the connection on their end. Maybe a list of activated devices they could then deactivate. She said no. Sheesh. I finally gave up. I googled and apparently the only way to deactivate HBO GO on an ATV is on the ATV itself. I also read a couple articles that say HBO doesn't really care right now if people share HBO Go and there's no limit to the number of activated devices so I guess I'll just let it go. I TRIED to do the right thing, lol. That's all I can do, short of canceling HBO I suppose. But not with True Blood coming back!
EDIT: Maybe for the ATV in particular, since I don't have to store a password or re-log in like I do on my iPhone when I'm away, it IS connected to my home network and so the activation connection will be broken if it leaves the house. Has anyone used their HBO Go on an ATV at someone else's house?