Moving from Unity to GNOME with no experience. So, how do I remove those apps icons (Steam, VLC etc.) from the top bar? Here are the icons that I'm talking about:
I don't have steam installed, but in VLC I go to Tools -> Preferences and uncheck "Show systray icon". Then exit and relaunch VLC. The icon should no longer be there, at least it wasn't in my environment (Ubuntu 17.10). Check steam for a similar option.