Dtyjlui

With gdm3, I was able to remove the last connected users from the list by removing the file '/var/log/ConsoleKit/history'

With lightdm, the last users appears even when :

• removing /var/log/ConsoleKit/history


• removing /var/lib/lightdm/.cache/unity-greeter/state

Where does lightdm store this list ?

Edit:
It seems like it's using the content from the last command. Then purging the content of the file /var/log/wtmp is sufficient to remove any previously connected user from the list :

# > /var/log/wtmp

But, after doing this, I have the unwanted side effect that users loging in via lightdm doesn't appears at all in this list.

I must say that I'm in a enterprise network environment using NIS.

Edit2:
Well, it seems that lightdm uses wtmp to display recent network users list, but does not update it. So, lightdm will show a network user only if it logged in in another fashion (ssh, login), like I did on this computer before. cf:

• https://bugs.launchpad.net/lightdm/+bug/871070


• http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=648604

Edit3:
I just added the following line to the file /etc/pam.d/lightdm To force lightdm to store users in wtmp :

session optional        pam_lastlog.so silent

So, to remove last connected network users from the list, just purge the /var/log/wtmp file :

# > /var/log/wtmp

Besides, to make lightdm remember last connected network users, one can add the following line to the file /etc/pam.d/lightdm :

session optional        pam_lastlog.so silent

I set /etc/lightdm/lightdm.conf as following to make the greeter screen not show the user list. Need to manually type in your username and password.

[SeatDefaults]

greeter-session=unity-greeter

user-session=ubuntu

allow-guest=false

greeter-show-remote-login=false

greeter-hide-users=true

hide-users=true

The last user to log in with lightdm is stored here:

/var/lib/lightdm/.cache/lightdm-gtk-greeter/state

Note the dot in .cache.

It is safe to simply delete the file.

I was also searching for this and finally figured it out how to do this in Ubuntu 16.04.

It seems lightdm is getting the user list from /var/cache/lightdm/dmrc/. This folder contains a file with the name of each user that has logged into the machine. Just remove the files for the unwanted users from that dir and the greeter no longer shows them.

EDIT: And this is of course after the already suggested stuff has been done (clearing /var/log/wtmp and /var/log/btmp). If the users still stick after these, find any files/folders containing the users' names in the filesystem and remove them.

I was also hitting this problem on 16.04, but with network accounts from AD via SSSD.

After a lot of trial-and-error, I used the following to get rid of the account :

List all accounts:

# qdbus --system org.freedesktop.Accounts

..

/org/freedesktop/Accounts/User1000

/org/freedesktop/Accounts/User10000

Now to remove the user with UID 10000 :

Optionally (if it's an AD user) : adduser deleteme and set UID to 10000 in /etc/passwd; otherwise next step will fail

Delete user via dbus:

dbus-send --system --print-reply --type=method_call --dest='org.freedesktop.Accounts' /org/freedesktop/Accounts org.freedesktop.Accounts.DeleteUser int64:<ENTER UID HERE> boolean:false

This will delete both "deleteme" from passwd as get rid of the entry in lightdm and in "user switcher" menu (top-right when logged in)

Running xubuntu 18.04.

session optional        pam_lastlog.so silent

This line goes in /etc/pam.d/login and causes my Login text entry box to be EMPTY. That is my desired behavior.

[SeatDefaults]

allow-guest=false

greeter-hide-users=true

greeter-show-manual-login=true

These lines are found in /usr/share/lightdm/lightdm.conf.d/50-no-guest.conf. For some reason my file had goofy permissions, fixed with...

sudo chmod 644 50-no-guest.conf

Remember certain answer relate to certain releases. This can occur from changes in standards or required functionality changes. Probably my goofy permissions came from some weirdness in the upgrade from 16.04 to 18.04.

How did I find the file?

After searching for 18.04 specific things on google it occurred to me theirs a file list for each package. Use Synaptic, find the the package lightdm, right click Properties. In dialog select 'Installed Files' tab. OR in a terminal...

dpkg-query -L lightdm