Using the same approach that @Justin tried to show you can change your systemd runlevel to one that isn't graphical. This will stop any graphical UI from being loaded/used by your BeagleBoard.
NOTE: Many Linux distros now use Systemd and below I'm showing you how to enable/disable the various runlevels. Don't get hung up that it's from the Fedora FAQ on the subject, the commands are identical.
From the Fedora topic on Systemd:
systemd has the concept of targets which is a more flexible
replacement for runlevels in sysvinit.
Run level 3 is emulated by multi-user.target. Run level 5 is emulated
by graphical.target. runlevel3.target is a symbolic link to
multi-user.target and runlevel5.target is a symbolic link to
You can switch to 'runlevel 3' by running
$ sudo systemctl isolate multi-user.target
You can switch to 'runlevel 5' by running
$ sudo systemctl isolate graphical.target
How do I change the default target?
$ sudo systemctl set-default <name of target>.target
NOTE: I modified the above verbatim's slightly by adding