PX4 PRO is a software middleware for autonomous systems and robots used to build a wide variety of drones. According to its official documentation:
PX4 can fly anything from a racing to a cargo drone - be it a multi copter, plane or VTOL.
Connect your Erle-Brain2 to internet, open one terminal and execute the following commands:
sudo apt-get update sudo apt-get install px4-erle-robotics
Open a terminal and type the following:
sudo apt-get purge -y px4-erle-robotics
PX4 official link.