You can erase data on it (if it's still connected to the internet) with Android Device Manager. As for getting it off your Google account, erasing the tablet (using android Device Manager) will do that.
Chances are, though, that either someone stole it and put it on their own account (so you can't get to it) or it's sitting somewhere with a dead battery or it's turned off - and you still can't get to it. I'd be very surprised if ADM found it.