how to disable and prevent selection on root node in devexpress treelist (angular)

list.component.ts

onCellPrepared(e) {
    if (
      e.rowType === "data" &&
      e.column.visibleIndex === 0 &&
      e.value === "ROOT"
    ) {
      const el = e.cellElement as HTMLElement;
      const ck = el.getElementsByClassName("dx-select-checkbox")[0];

      const instance = dxCheckBox.getInstance(ck);
      instance.option("disabled", true);
    }
  }

onSelectionChanged(e) {
    // disable root node
    const disabledKeys = e.selectedRowsData
      .filter((i) => i.root === true)
      .map((p) => p._id);

    if (disabledKeys.length > 0) {
      e.component.deselectRows(disabledKeys);
    }
  }