copied from elsewhere:
To do a full scrub of everything you've ever posted:
- Request your GDPR data package here: https://www.reddit.com/settings/data-request
- Wait for it to arrive
- Use shreddit to fully delete everything: https://github.com/andrewbanchich/shreddit
This will take a long time if you've posted and commented a lot. This works better than PowerDeleteSuite in my experience, as PDS missed a lot of stuff that was older than a certain point.
There is a way to make it not delete your comments and change what the edited message is, check the readme in the github link.