Purge Documents and Folders
Deleted documents and folders are removed from view, but not permanently removed from the vault. To permanently remove a document or folder and all of its data so that it cannot be undeleted, you must purge it. A document or folder must first be deleted before it can be purged.
Purged documents and folders cannot be restored except by restoring the entire vault from backup. Doing so loses all changes made to the vault since the backup was made. Be absolutely certain that you want to proceed.
Do not purge documents during synchronization. Purged documents are completely removed from the vault, and synchronization is no longer possible.