If the editorial is signed by the editorial board, it is not necessary to indicate in a works-cited-list entry that the work you are citing is an editorial:
Editorial Board. “How to Tell Truth from Fiction in the Age of Fake News.” Chicago Tribune, 21 Nov. 2016, www.chicagotribune.com/
If the editorial is unsigned and you want your reader to know that the piece is an editorial rather than a news article, you can refer to the work as an editorial in your discussion, or you can include “Editorial” as an optional element at the end of the entry:
“It’s Subpoena Time.” The New York Times, late ed., 8 June 2007, p. A28. Editorial.
If it’s an op-ed—that is, an opinion piece written by someone who is not an editor of the publication—you can include “Op-ed” at the end of the entry:
Gergen, David. “A Question of Values.” US News and World Report, 11 Feb. 2001, p. 72. Op-ed.
Published 8 March 2017