If you have a single user computer odds are you also have no need for a display manager to be cluttering your system. The solution is to simply have your desktop GUI of choice auto-start when the computer turns on. To do this we are going to use a simple, but effective, piece of software cleverly called "NoDM".
Before we begin, you first need to disable or uninstall any current display managers running on the system (look into your display manager documentation on doing this, it varies with each display manager).
Next you need to install NoDM. On a Debian/Apt based system it is as simple as running: