OK, from the dad account, have a look at the link below and please paste the output to cat /etc/lightdm/lightdm.conf
If the file looks similar to the one in the link below or to mine, you can proceed. Do not hesitate to post it here first, before going further. Of course, I do not have autologin, so I'm missing the last line :
The process will be :
bapoumba_lxde@SonyBlue:~$ cat /etc/lightdm/lightdm.conf
If the last line says autologin-user=dad2, first backup the file :
Remove dad2 from the line :
sudo cp /etc/lightdm/lightdm.conf /etc/lightdm/lightdm_old.conf
Save and exit :
sudo nano /etc/lightdm/lightdm.conf
ctrl o (letter o) to save
ctrl x to exit.
Logout, and see if you can choose the user dad from the login screen.
Then from the user dad, you can remove dad2 : https://help.ubuntu.com/10.04/server...anagement.html