Users who have made no more than one post can delete their own accounts from their user preferences page.

lib/guardian/user_guardian.rb

@@ -0,0 +1,38 @@
+# mixin for all Guardian methods dealing with user permissions
+module UserGuardian
+
+  def can_edit_user?(user)
+    is_me?(user) || is_staff?
+  end
+
+  def can_edit_username?(user)
+    return true if is_staff?
+    return false if SiteSetting.username_change_period <= 0
+    is_me?(user) && (user.post_count == 0 || user.created_at > SiteSetting.username_change_period.days.ago)
+  end
+
+  def can_edit_email?(user)
+    return true if is_staff?
+    return false unless SiteSetting.email_editable?
+    can_edit?(user)
+  end
+
+  def can_block_user?(user)
+    user && is_staff? && not(user.staff?)
+  end
+
+  def can_unblock_user?(user)
+    user && is_staff?
+  end
+
+  def can_delete_user?(user)
+    return false if user.nil?
+    return false if user.admin?
+    if is_me?(user)
+      user.post_count <= 1
+    else
+      is_staff? && user.created_at > SiteSetting.delete_user_max_age.to_i.days.ago
+    end
+  end
+
+end