you need to click on the selected item again to clear the filter. Generally when Use as filter option is created for table or chart. Dashboard filter action is created.
You can find it under Dashboard--> Actions
Select the action you see.
Thanks for your reply Amit. I was more looking towards creating a reset button to undo all the selections made on the tree-map. Do you know a way out? TIA
click anywhere on dashboard or sheet all selections are gone