"If you delete your account, we'll initiate deletion of this information after 30 days. But please note: (1) there might be some latency in deleting this information from our servers and back-up storage; and (2) we may retain this information if necessary to comply with our legal obligations, resolve disputes, or enforce our agreements."
Deletion only begins 30 days after account closure, with additional unspecified latency, and Dropbox reserves the right to retain data indefinitely for legal reasons, disputes, or agreement enforcement.