Super timely. Even on my linux box I noticed yesterday that zoom, even though I had "closed" the application, was still running `ps -ef | grep zoom` so I killed it.
After reading this, I've deleted it too. Super weird.
I saw a tray icon after I closed it out when I ran it this morning, on Xubuntu with the Cinnamon desktop. I right-clicked it and selected Exit, and it did indeed exit.
ETA: Checking the dpkg file listing shows that everything goes into /opt/zoom except a /usr/bin/zoom symlink to /opt/zoom/ZoomLauncher.
After reading this, I've deleted it too. Super weird.