[samat]

document.querySelectorAll("td.subtext").forEach( function(currentValue, currentIndex, listObj) { currentValue.hidden = true; } );

[AndrewCHM]

or just inject (via extension or JS)

    .itemlist .subtext {display: none;}

[polote]

you can't use forEach with a NodeList ;)

[AgentME]

Easiest solution is to wrap the NodeList with Array.from(...) first. Just wanted to point out how handy that function is.

Also if we're going to make a snazzy one-liner, let's cut out the unused arguments:

  Array.from(document.querySelectorAll("td.subtext")).forEach(currentValue => { currentValue.hidden = true; });

[sillysaurus3]

JS's lack of macros strikes again.