Make room with pkgcacheclean in Arch

All installed packages will be cached in /var/cache/pacman/pkg
If you look in this cache you will be surprised to find as much as four or five versions of the same program.
If you want to make room than it is useful to purge the cache of too many versions of the same program with pkgcacheclean: https://aur.archlinux.org/packages/pkgcacheclean/
Do as root: #pkgcacheclean -v 
to actually do it.

Usage: pkgcacheclean [options] [number]

The default number is 2. That means, for all installed packages, the currently used version and the newest of the remaining cache is retained. All caches of not-installed packages are removed.
Currently, supported options only includes -v/--verbose, -q/--quiet, -n/--dry-run, -k/--all-as-installed.

more info