Sometimes the document that you sent out is wrong and needs to be deleted.
You can do that from either the dealboard if it's a sales document or in the document summary via the document action menu.
Once deleted you can find it under the tab "Document -> Deleted".
You can't make a deleted document active again. If you have mistakenly deleted a document you will have to create a new version of it and send out the new copy.
You cannot download a deleted, lost, or recalled document.
How to delete a sent document