Clicking the button, then ungroup the PT,

groupThenUnGroupSimple.EXCEL.yaml

name: groupThenUnGroupSimple
description: 'Clicking the button, then ungroup the PT,'
host: EXCEL
api_set: {}
script:
  content: |
    $("#setup").click(() => tryCatch(setup));

    async function setup() {
      await Excel.run(async (context) => {
        context.workbook.worksheets.getItemOrNullObject("Data").delete();
        const dataSheet = context.workbook.worksheets.add("Data");
        context.workbook.worksheets.getItemOrNullObject("Pivot").delete();
        const pivotSheet = context.workbook.worksheets.add("Pivot");

        const data = [
          ["Date", "Sales"],
          ["8/19/2020", 18],
          ["8/18/2020", 18],
          ["2/5/2018", 187],
          ["1/1/2018", 142],
          ["1/2/2018", 150],
          ["1/3/2018", 180],
          ["1/4/2018", 110],
          ["1/5/2018", 121],
          ["1/6/2018", 134],
          ["1/7/2018", 155],
          ["1/8/2018", 155],
          ["1/9/2018", 155],
          ["1/10/2018", 155],
          ["1/11/2018", 177],
          ["1/12/2018", 238],
          ["1/13/2018", 238],
          ["1/14/2018", 238],
          ["3/20/2019", 128],
          ["3/21/2019", 177],
          ["3/22/2019", 180],
          ["3/23/2019", 180],
          ["3/24/2019", 220]
        ];

        const range = dataSheet.getRange("A1:B23");
        range.values = data;
        range.format.autofitColumns();

        pivotSheet.activate();
        await context.sync();

        const rangeToAnalyze = context.workbook.worksheets.getItem("Data").getRange("A1:B23");
        const rangeToPlacePivot = context.workbook.worksheets.getItem("Pivot").getRange("A2");
        context.workbook.worksheets.getItem("Pivot").pivotTables.add("Farm Sales", rangeToAnalyze, rangeToPlacePivot);
        await context.sync();

        const pivotTable = context.workbook.worksheets.getActiveWorksheet().pivotTables.getItem("Farm Sales");
        const hierarchy = pivotTable.hierarchies.getItem("Date");
        const field = hierarchy.fields.getItem("Date");
        const hierarchy2 = pivotTable.addDateGroup(field, "ByYears");
        pivotTable.rowHierarchies.add(hierarchy2);
        const hierarchy4 = pivotTable.hierarchies.getItem("Sales");
        pivotTable.dataHierarchies.add(hierarchy4);
        await context.sync();
      });
    }

    /** Default helper for invoking an action and handling errors. */
    async function tryCatch(callback) {
      try {
        await callback();
      } catch (error) {
        // Note: In a production add-in, you'd want to notify the user through your add-in's UI.
        console.error(error);
      }
    }
  language: typescript
template:
  content: "<section class=\"ms-font-m\">\n\t<p>This sample shows how to create PivotTables and add hierarchies to form rows, columns, and data sets.</p>\n</section>\n\n<section class=\"setup ms-font-m\">\n\t<h3>Set up</h3>\n\t<button id=\"setup\" class=\"ms-Button\">\n        <span class=\"ms-Button-label\">Setup sample</span>\n    </button>\n</section>"
  language: html
style:
  content: |-
    section.samples {
        margin-top: 20px;
    }
    section.samples .ms-Button, section.setup .ms-Button {
        display: block;
        margin-bottom: 5px;
        margin-left: 20px;
        min-width: 80px;
    }
  language: css
libraries: |
  https://appsforoffice.microsoft.com/lib/beta/hosted/office.js
  @types/office-js

  office-ui-fabric-js@1.4.0/dist/css/fabric.min.css
  office-ui-fabric-js@1.4.0/dist/css/fabric.components.min.css

  core-js@2.4.1/client/core.min.js
  @types/core-js

  jquery@3.1.1
  @types/jquery@3.3.1