@phocean and @Norbert_X
Thank you so much for the replies.
While I have purged:
sudo apt-get purge gdm3
sudo apt-get purge solaar solaar-gnome3
sudo apt-get purge ubuntu-session xwayland
When I tried to completely remove (via Synaptic) gnome-session-bin gnome-settings-daemon,
Synaptic said, it'll also remove:
gnome-startup-applications
gnome-control-center
gnome-shell
So is it safe to remove these three also? For now I have left gnome-session-bin and gnome-settings-daemon as it is.