Under settings, you’ll see a visibility setting for the selected element.
Select the element and mark it as hidden.
It will still exist in the left side nav, but it will not appear on the canvas and that element and its children will not publish to the site.
One technique I like is to create a class called something like “unused”, and prefix it with an emoticon, you can copy-paste from here-
Then wrap your unused section in a new DIV and assign that class.
Then go to settings and mark it hidden.
This makes it easy to spot in the left nav. Note that unlike styles, settings are not part of the class, so you need to remember that settings visibility hidden step, the class won’t “embody” that setting.
If you don’t fully understand the difference between display: none and visibility: hidden, this might help.