One of my flags in this room "Martin Hopf's prime numbers" to a post from Adam L was apparently declined. No idea why.

@Peter If you own the room, you can simply move the messages you don't want to Trash.

← 2 messages moved from CURED

@Peter: Just like I did to move those messages to this room. =)

Do you know how to do it?

No, I don't

@Peter If you are on an ordinary browser click on "room▼" and then "move messages".

I did not see "move messages" yet. Must I click within the room or outside ?

OK, have found it now

@user21820 Most posts moved. Moderators should take a closer look on Adam L

@Peter It is worth pointing out that there are two types of flags in chat.

"flag as spam/offensive" is evaluated simply by regular users

@Peter Indeed. But moderators are more lax when it comes to chat, as long as users behave reasonably. At the same time, you have a greater freedom to handle rooms that you are an owner of. So I wouldn't expect them to do much in this case, since it seems sufficient that all the junk is trashed.

However, if the user repeatedly posts junk in your room, you should flag and they probably will do something about it.

"flag for moderator attention" is handled by a moderator. (But not necessarily Mathematics mods.)

@MartinSleziak Hmm, then maybe.. tell the Math SE mods in their office instead of just flagging.

You can also check which tools you (as a RO) have at your disposal: A guide to moderating chat.