discourse/app/assets/javascripts/admin/models/email-template.js

import { ajax } from "discourse/lib/ajax";
import RestModel from "discourse/models/rest";
const { getProperties } = Ember;

export default RestModel.extend({
  revert() {
    return ajax(`/admin/customize/email_templates/${this.id}`, {
      type: "DELETE"
    }).then(result =>
      getProperties(result.email_template, "subject", "body", "can_revert")
    );
  }
});