Before going into all of that you can run, from the system (not a Live
system) the following command to remove the packages that are archived:
$ sudo apt-get clean
You can also search for the kernels installed on your system (packages whose
name start with "linux-") and remove all of them but those related to the
latest version (the one you are currently using).
The few GB you will save in this way may be all you need. For a few GB more,
you can take them from the sole swap partition (as I already wrote). For even
more, well, go through the steps I listed in the previous post.
