Disabling left/right portlet slot in Plone 5.2

Is this documentation still working in Plone 5.2?

https://docs.plone.org/develop/plone/functionality/portlets.html#disabling-right-or-left-columns-in-a-view-or-template

Don't think so (does not work)...so what is the preferred way to disable the portlet lots altogether for all views of a given add-on through CSS (not using Diazo, no theme involved here) in order to occupy the full available width?