When customizing htop my setup through the F2 menu, I accidentally put up some unwanted meters. I tried using backspace/delete according to the bottom menu, but it didn't affect the entry. I'm using Mac OS X, if that matters.
I found that on a mac keyboard you could use the Fn+Delete to remove column entries from the setup menu.
My solution was to delete the htop configuration file using
rm -fv ~/.config/htop/htoprc
While certainly not a true solution, it is a workaround.
My solution was (iterm2 using natural keys) to us Fn+ctrl+delete to remove column entries from the setup menu.