Anybody know how to add|remove custom markers from series in AnyChart JS? I cant find it in documentation.
I believe you mean series markers. To turn them on and off use markers() method, available for all series except the markers series itself.
Example: http://jsfiddle.net/85Lbeu8p/1/
var markers = series.markers();
markers.enabled(true);
markers.fill('gold');
Method reference: https://api.anychart.com/7.8.0/anychart.core.radar.series.Line#markers