Yes, it is possible to toggle on or off a data series in a chart. Here's how:

1. Click on the chart to select it.
2. Right-click on the data series you want to hide and select "Format Data Series" from the context menu.
3. In the "Format Data Series" dialog box, go to the "Options" tab.
4. Uncheck the "Plot visible cells only" option.
5. Click "OK" to close the dialog box.

To toggle the data series on and off, you can use a checkbox or a button linked to a macro that hides or shows the data series. Here's how to create a checkbox:

1. Go to the "Developer" tab and click on "Insert" in the "Controls" group.
2. Select the checkbox control from the list.
3. Draw the checkbox on the worksheet near the chart.
4. Right-click on the checkbox and select "Format Control" from the context menu.
5. In the "Format Control" dialog box, go to the "Control" tab.
6. In the "Cell link" field, enter a cell reference where the checkbox state will be stored (e.g. A1).
7. Click "OK" to close the dialog box.

Now, when you click on the checkbox, the state will be stored in the cell you specified. You can use this cell in a formula to control the visibility of the data series. Here's an example formula:

This formula checks the state of the checkbox in cell A1. If it's true, it returns the data range for the data series (B2:B6 in this example). If it's false, it returns the #N/A error, which will hide the data series.

To use this formula, select the data series and go to the "Select Data" dialog box. In the "Edit Series" dialog box, enter the formula in the "Series values" field, replacing the data range with the formula. Click "OK" to close the dialog boxes.

Now, when you click on the checkbox, the data series will be hidden or shown depending on the state of the checkbox.