Robert,
For a few minutes I had the theory that the problem at bug #1259562 with guest users not being removed from accountsservice would be fixed, if --system was dropped when creating a guest session. However, I tested to use deluser to delete a regular user, and also in that case the file in /var/lib/AccountsService/users was not removed.
Robert, AccountsService /users was not removed.
For a few minutes I had the theory that the problem at bug #1259562 with guest users not being removed from accountsservice would be fixed, if --system was dropped when creating a guest session. However, I tested to use deluser to delete a regular user, and also in that case the file in /var/lib/