brew cleanup -s

==> This operation has freed approximately 2.4G of disk space.


rm -rf $(brew --cache)
$ brew cleanup -h
brew cleanup [--prune=days] [--dry-run] [-s] [formulae]:
    For all installed or specific formulae, remove any older versions from the
    cellar. In addition, old downloads from the Homebrew download-cache are deleted.

    If --prune=days is specified, remove all cache files older than days.

    If --dry-run or -n is passed, show what would be removed, but do not
    actually remove anything.

    If -s is passed, scrub the cache, removing downloads for even the latest
    versions of formulae. Note downloads for any installed formulae will still not be
    deleted. If you want to delete those too: rm -rf $(brew --cache)