Is there an easy way to kill all checked items in all checklists from a .org file? Similar to "clear completed tasks" in Google Tasks. Also it would be handy to know how to kill or archive all DONE items at once, and not per item.
I don't believe that checkboxes can be cleared or archived by default in Org. They are seen as lightweight tasks so more for subdividing tasks into smaller pieces or to create a shopping list 1 . They also do not show up in global TODO lists or Agenda views, so there is much less tracking of them.
On the other hand, there is a simple enough way to remove all DONE items from a file or from all Agenda files. You can use bulk remote editing 2 on any associated agenda files, or using buffer restrictions to apply only to the current file (
C-a a <)
Using a TODO match in the agenda
C-a a T then telling it to match DONE will provide you with a list of all headlines that match.
If you plan on needing to archive done tasks frequently you can set up a custom agenda search:
(setq org-agenda-custom-commands '(("d" todo "DONE")))
Then mark the desired entries (or mark them all) and use bulk archive