Unfortunately it has been demonstrated through whitehat research that simply deleting your old account is relatively useless. They have shadow profiles of users based on probabilistic data. For example, say your spouse with her decades old account keeps making posts about what you ate on date night, your trip to Cabo, or worse yet she posts a bunch of pictures of her, you, and the kids. Facebook makes a shell profile based on this conception of "you" and begins aggregating all the info it can about this person.
More over, every time an acquaintance of yours gives their FB app permissions to access their contacts (to suggest Friends or whatever) if your contact info is on the list, FB now has your real name, your email, your mobile phone number, etc. You never opted in, but it doesnt matter - other people are opting you into FB data collection all the time, unless you literally don't tell anyone your real phone number or email address.
Me, still using a site licensed copy of Office 2007 from a job I had over a decade ago.