Hi,
Thank you for contacting us with your question.
1) To remove a series from legend, set
series.showInLegend to
false.
https://api.highcharts.com/highcharts/s ... owInLegend
2) To change the name in the legend, just simply change the series name in
series.name
https://api.highcharts.com/highcharts/s ... ogram.name
3) I'm not sure where you would like to add your line. You can use the
plotLine option or our
Highcharts.SVGRenderer to create custom shapes on the chart. If these options do not satisfy you, please take a screenshot of the chart and show me where would you like to have your line, and I'll do my best to help you.
Take a look at the modified demo below:
https://jsfiddle.net/BlackLabel/1nhv0ty3/
Do not hesitate to contact us with any further questions,
Kind regards!