Finding/Removing Packages:
The way I check which packages are installed is using
aptitude. Try the following to list installed packages for XFCE:
$ aptitude search xfce | grep -E '^i'
You can remove all installed packages for XFCE as follows:
$ sudo aptitude purge $(aptitude search xfce4 | awk '{if($1 == "i") print (($2 == "A") ? $3 : $2)}')
The Other Method:
Changing the splash screen:
That said, while purging the packages will probably resolve your problem, its not the only way to go about it. Try the following to change the splash screen:
$ update-alternatives --list desktop-splash
$ sudo update-alternatives --set desktop-splash <path_to_new_splash_here>
For example, if I wanted to revert the Debian Wheezy splash screen to that of Debian Squeeze, I would do it as follows:
$ update-alternatives --list desktop-splash
/usr/share/images/desktop-base/gnome-splash-curves.png
/usr/share/images/desktop-base/moreblue-orbit-splash.png
/usr/share/images/desktop-base/spacefun-splash.svg
$ sudo update-alternatives --set desktop-splash /usr/share/images/desktop-base/spacefun-splash.svg
Configuring the display manager:
Modifying the list of desktop environments you may choose from at the login screen is heavily dependent your display manager. For example, using
slim, I can modify the
sessions line in my
/etc/slim.conf to suit my needs. Using
lightdm or
gdm, I can remove the file in
/usr/share/xsessions corresponding to the desktop environment that I want to remove. (Purging the package should also remove any files it installed in that directory.)
Finally, if you installed a new display manager and would like to revert, you can easily choose a display manager from all installed alternatives by running the follow command:
$ dpkg-reconfigure lightdm # lightdm may be replaced by the package name of any display manager you have installed, such as gdm, kdm, or slim