However, I have a case where I'm tracking legal agreements that apply to two or more users each. Even if a user stops visiting the site, I need to keep track of their last known information, in case there's ever a legal squabble between users. Even if they delete their account, we'll have their information on file, which feels ethically shaky, since account deletion seems to imply that they've been wiped from our system.
What would the best balance between honesty and the feeling of user-control? Should I mention in the account deletion process that we'll be keeping their old info? Should I prevent account deletion to avoid the slightest illusion of having purged their info? Should I just not make a big deal of it and change the wording of 'account deletion' to 'unsubscribe from notifications'?