Most guides I see are about improving your privacy in the future. Is there any way of erasing my privacy mistakes of the past?

As most people (probably) I wasn't always doing the best for my online privacy. So between data breaches and big-data I probably have gigabytes of data somewhere out there on the internet.

Most guides I've read are things I can do now so my this doesn't happen again, but... all these years of data already collected on me are still out there, whether I follow these tips or not. Is there anything I can do about this?

future privacy