Proper way to remove all series data from a highcharts chart?

Try this to remove all chart series,

while(chart.series.length > 0)
    chart.series[0].remove(true);

it works for me. the code

for (var i = 0; i < chart.series.length; i++)

won’t work because the chart.series.length is decreased each time remove() is called. That way, the i will never reach the expected length.