While a DM can hide a chat message, which is a huge improvement over how it used to be, I agree that it would be very useful to expunge a message entirely. I tend to keep my chat log around for months as a record of the current series of sessions, and in-between i do testing when the players aren't on to prep for the next game, and have to hide those messages, but I still get to see large blocks of "this message was hidden", which is a nuisance. I hadn't considered the need to remove (or fully hide) player messages, but I see that. It would be useful also to be able to change logging to a "hide all messages from players from other players." status and then back, without revealing what was hidden. That way you could do breakouts with a player or sub-group and not let the whole group know what they were up to. Back in table-top days, I once playeed a game with players in two rooms (and a harried DM running back and forth) who were pursing different paths through the same adventure, and all we knew of what the others were doing were comments from the DM like (the town you can see in the distance seems to be on fire). It was a lot of fun, actually. You could do the same today with two copies of the game, but it would be cool if you could somehow split the chat log along with the map and audio, for a single game, and keep the contents of the two threads hidden from each other when the teams re-unite. So +1 for actually deleting or removing any player-visible indication at all, of an individual message. And it would be great if Roll20 could generalize that even more. (edit: typos)
