Where your content lives
Your documents, the organisation model and everything runs produce are stored against your account. Directories you own hold their own content; directories you were invited to belong to their owner.
The Data controls page
Settings → Data controls sets the storage locations for your documentation folders — the content and docs targets. It exists for running the product against your own storage and is not something most accounts need to touch. Leave it alone unless you know why you are changing it.
Getting work out
Enable the export control per directory under Page elements in Directory settings, or read anything programmatically over the API.
Deleting
Documents can be deleted individually from Memory, or a whole directory can be deleted. A directory's content lives in its owner's storage, so deleting one removes it for its members as well.