How can a user self-delete?

[cpradio]

No it is hard coded.

New users with only 1 post can delete their account?

FYI, here is the code for it: https://github.com/discourse/discourse/blob/master/lib/guardian/user_guardian.rb#L41-L48 And https://github.com/discourse/discourse/blob/master/lib/guardian/post_guardian.rb#L63-L69

The idea is, if they were active enough to have more than that, deleting their account would potentially render some topics (that they were involved in) useless.