Self deleting accounts with only a few posts is possible, as is self-deleting topics and posts (there's a trash icon behind the ellipses), with some constraints for newer and low trust-level users on the forum.
We use discourse (discourse.org) to run the forum, with their settings, for better and sometimes for worse.
When in doubt, use the flag icon and a custom message to let admins know about an issue, or email community@rstudio.com, and we'll take it from there as quickly as we can.