removeBox(chart, layoutItem) {
    const index = chart.boxes ? chart.boxes.indexOf(layoutItem) : -1;
    if (index !== -1) {
      chart.boxes.splice(index, 1);
    }
  }
Remove a layoutItem from a chart
@param {Chart} chart - the chart to remove the box from
@param {LayoutItem} layoutItem - the item to remove from the layout