Would it be possible to report a player outside of a game? (player behavior in chat)

I say this because I was on my boyfriend's account (he and I know each others accounts and passwords) a summoner that goes by the name "The Ali Gamer" had messaged asking for sexual things. I won't get into it but clearly he tried to play it off that he wasn't actually trying to do anything after I had told him "bye". I just feel for these cases there needs to be something to be done.