Its also reporting the same problem in octoprint UI,
The problem is that am not so much familiar with Linux and therefore don't know the proper way to clear the logs. I would like to get help on that please?
So, where is the disk space used up? sudo du / -h --max-depth=2 --exclude=/proc --exclude=/dev --exclude=/sys
will give you a list of directories and their respective sizes.
On my systems (with a more or less regular apt-get update && apt-get upgrade) one place to look is /var/cache with hundreds of MB of packages in it.
sudo apt-get clean will free that space (deleting older versions you probably won't need ever again)
Another place is /var/log ls -lSr /var/log will list all the files there from smalles to biggest.
sudo rm /var/log/*gz will remove all archived old logfiles.