Interesting how different Linux desktops cater (or not) for "I don't want to see the clock on the screen".
MATE -> Right click, remove
Unity -> Tickbox in settings
GNOME Shell -> You can't. Write an extension
elementaryOS -> Uninstall a Debian package
@popey You forgot KDE. 😏
@ebassi Only because I haven't tried it on that one yet. :) Also, expected that KDE would have 5 clocks on screen at all times! ;)