On a Column Chart is it possible to hide/unhide legend values by clicking on it?
For eg. if I click on www3 in legend this action will hide www3 and I'll see only www1 and www2 on a chart.
You can't do it via the legend, as that does not support drilldown - you'd have to play around with JS probably to get that to work.
I assume you want to be able to unhide it again, so you can't do it directly on that chart, but you could do it by having another set of buttons in another panel that would provide a filter set to show/hide those.
I've often done this either through a multiselect input above the chart or a link input where the inputs are tabbed horizontally, e.g.
You can see how that is done in the Itsy Bitsy app for Splunk - https://splunkbase.splunk.com/app/5256
