Gnome Shell running, with no one logged into it?

Ubuntu 18.04, logged out of GUI, accessed system via webmin and see an awful lot of memory being consumed by Gnome. Shouldn't this end when all users are logged out of the GUI? Can I kill all this GUI stuff in a way that will allow it to restart when a user logs into the GUI? Or do I just need to ignore this and let it eat up all this RAM doing nothing?

ID  Owner   Size    Command
2371    gdm     4.06 GiB    /usr/bin/gnome-shell
2524    www-data    2.99 GiB    /usr/bin/zmc -m 3
1512    mysql   2.92 GiB    /usr/sbin/mysqld --daemonize --pid-file=/run/mysqld/mysqld.pid
2528    www-data    2.49 GiB    /usr/bin/zmc -m 4
947     root    2.09 GiB    /usr/lib/snapd/snapd
2532    www-data    2.05 GiB    /usr/bin/zmc -m 5
2519    www-data    1.99 GiB    /usr/bin/zmc -m 1
2464    gdm     1.66 GiB    /usr/bin/Xwayland :1024 -rootless -terminate -accessx -core -listen 4 -listen 5 ...
2659    gdm     1.3 GiB     /usr/lib/gnome-settings-daemon/gsd-media-keys
2512    gdm     1.25 GiB    /usr/bin/pulseaudio --daemonize=no
2655    gdm     1006.75 MiB     /usr/lib/gnome-settings-daemon/gsd-color
2664    gdm     851.18 MiB  /usr/lib/gnome-settings-daemon/gsd-power
2658    gdm     840.84 MiB  /usr/lib/gnome-settings-daemon/gsd-keyboard
2649    gdm     837.45 MiB  /usr/lib/gnome-settings-daemon/gsd-xsettings
2682    gdm     773.05 MiB  /usr/lib/gnome-settings-daemon/gsd-wacom
2536    www-data    695 MiB     /usr/bin/zmc -m 8
2545    www-data    693.57 MiB  /usr/bin/zmc -m 10
2629    gdm     690.38 MiB  /usr/lib/ibus/ibus-x11 --kill-daemon
2652    gdm     690.02 MiB  /usr/lib/gnome-settings-daemon/gsd-clipboard
2341    gdm     538.77 MiB  /usr/lib/gnome-session/gnome-session-binary --autostart /usr/share/gdm/greeter/a ...```