How long are documents kept?
Documents tied to an active lease or account stay accessible for as long as you need them for that relationship; some records, like signed leases, are retained longer for record-keeping purposes as described in the Privacy Policy.
From the guide Documents & Storage.
Deleting documents
Some documents (like signed leases) are retained for record-keeping and legal reasons and can’t simply be deleted. Where deletion is available, remember that you may still be legally required to retain your own copy elsewhere.
Read the whole guide: Documents & Storage