I am very, very new to Linux. My son set it up, and is not available now. He had the kernals automatically updating, which eventually totally filled up /boot/. With the help of Experts I was able to delete older kernels and have working room in /boot/. I have a separate question posted to increase /boot/ to 500MB.
What I need is to arrange for new kernel updates to be installed, then the oldest image to be deleted. Right now I seem to have three images under /boot/, so if I automatically deleted the oldest I would always have three, which would be fine. This is a pure ubuntu 14.04 machine, no Windows, no dual boot.
I am very new, so please don't quote processes and procedures; I need exact command lines I can type verbatim.