At [1] you are told to create the file /usr/share/pam-configs/face_authentication, however, in the uninstallation instructions the file /usr/share/pam-configs/face-authentication is removed (i.e. the underscore is replaced by a dash).

[1] http://pam-face-authentication.org/downloads.php

try this:

alt + f2, alacarte add the name and the command (locate face-trainer first)

if you remove PAM the apps hide automatically or you can delete it from alacarte ;)

for remove PAM totally:

sudo gedit /etc/pam.d/gdm

and remove auth sufficient pam_face_authentication.so enableX

and purge the app :(

sudo apt-get --purge remove pam-face-authentication

if you want remove the ppa:

sudo apt-get install ppa-purge

sudo ppa-purge ppa:antonio.chiurazzi/ppa

I don't really get your comment... The uninstallation instructions on the website are fine, they just need to replace the dash by an underscore.

thanks for the underscore note... corrected it on the webpage