Many of our development teams don't work in conventional sprints, since their work is delivered on an ad-hoc basis. To accommodate these teams in the portfolio, we created a single sprint for them with no iteration dates in TFS 2013.
However, I've noticed that PBIs aren't removed from the Task Board when their status is set to Done. This creates a scenario on the task board where we have an increasing number of done tasks, and we will eventually arrive at a state where we can't display all our work on the task board due to the item limit.
Is there a way to prevent PBIs in the "Done" state from appearing on the task board? (Note that I'm specifically referring to the Task Board, not the backlog.)