What if I don’t want anything in any of the sidebars/footers/etc.?
If you do not want any *widgets* in any sidebar or footer widget area, remove them all. Even an empty text widget can still show up.
If you remove all widgets from any sidebar or footer area and the sidebar or footer still shows (as the footer almost certainly will), you will need to make a Child Theme so you can use custom page and/or footer templates.