Which is why "at scale" you design systems that let you mark records as deleted (without actually deleting them).

You then need to choose how you explain that to users (preferably before they sign up and start entering sensitive data) as well as the normal problems of deciding the policy about having backups of "deleted" data (if you don't actually delete it - either from the live data set or from archived backups - a court could require you to hand it over).