I can see when one of my friends is watching something in “Now Playing” however, if for whatever reason, it would be great to stop/disconnect them, if the server needs to be rebooted or they left their house by mistake and have left it running (I’m assuming this is taking resources on both sides).
There are already a lot of feature requests for this very thing here. My suggestion is, use the search, find the one that has the most “Likes” and like that one, so we don’t get the votes spread out too far.
I know there is at least one request, since I’m the one that made it, about booting stuck clients. Does the same thing you want to do. (I was specifically thinking of stuck Roku’s when I made it.)