Hiding swimlanes when they have no tickets that fall under them

Hi, 

I've currently got a task board which shows all of the tasks associated with a set of user stories and flow that is 

Funnel, In progress, Done

Currently i'm testing this out and have a structure as below with the user stories as swimlanes:

Given that not every user story has tasks associated with it. How can i hide these swimlanes that have no tasks ?

I'm also wanting to keep items in the done column only for one sprint before they disappear, how can this be configured.

Enjoying the product, thanks guys!