Ok, I got a tiny problem.
In a game-recruitment thread I clicked on a link to a campaign here on Roll20, and it started showing me under the active players, and lists the campaign as "Campaigns you've joined".
However, I never clicked the "Join Campaign" button inside (the only two links I can click in the campaign page is that and Chat Archive), and instead of Launch Campaign I still see Join Campaign in the overview. (However that might just be a distinction between being GM and being a Player)
The problem is, now whenever something happens in that game like comments, it lights up the ticker in the upper right corner.
I've no idea how to get that game off my list again.