Remove Unneeded Dependencies
When Regolith is installed via ISO, only the necessary desktop components or packages are installed by default. However when installing Regolith into an existing Ubuntu system, some desktop components that Regolith does not require will still be installed on the system. There is nothing wrong with keeping these additional packages, in fact they are important if you wish to switch back to the default Ubuntu session at some point, however some users prefer to remove them.
Install LightDM
The lightdm display manager can be installed by with a variety of themes, but we’ll install the package regolith-lightdm-config:
sudo apt install regolith-lightdm-configInspect the output of apt to verify you approve of the package changes. When presented with a menu, choosing between gdm3 and lightdm, select lightdm.
Remove Unneeded Packages
Now that we are using the lightdm display manager, we can remove the unneeded packages:
sudo apt remove gdm3 gnome-shell 'evolution-data-server*'Inspect the output of apt to verify you approve of the package changes.
The Regolith sessions need gnome-session-common, but on Ubuntu 26.04 no remaining package depends on it, so apt autoremove would remove it and logging in would fail. Mark it as manually installed first:
sudo apt-mark manual gnome-session-commonNow we can remove all of the dependencies of those packages:
sudo apt autoremoveIf logging in returns you to the login screen after this step, switch to a text console with ctrl alt f3, log in there and run sudo apt install gnome-session-common.
Reboot
At this point the unneeded dependencies have been removed from the system. Reboot to complete the procedure.
Undo
If you decide that you’d like to restore the existing setup, run the following and select gdm3 as the display manager.
sudo apt install gdm3 gnome-shell evolution-data-server ubuntu-session
sudo apt remove regolith-lightdm-configlightdm itself stays installed. Once gdm3 is the default display manager, you can remove it with sudo apt remove lightdm.