<article>
  <p>I have various properties set, globally.</p>
</article>
<aside>
  <p>I want the global properties set on paragraphs unset.</p>
</aside>

/* Global color styles for paragraph in authored CSS */
p {
	margin-top: 2em;
	color: goldenrod;
}

/* The p needs to be “reset” in asides, so you can use unset */
aside p {
	margin: unset;
	color: unset;
}