brew: how to delete outdated version of package
The command you want is cleanup -- running brew cleanup will remove packages that are on disk, but no longer installed.

&gt; brew help cleanup
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, scrubs 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)


For example:

&gt; brew cleanup
Removing: /usr/local/Cellar/awscli/1.10.19... (2,955 files, 22.3M)
Removing: /usr/local/Cellar/git/2.8.2... (1,418 files, 30.5M)
Removing: /usr/local/Cellar/imagemagick/6.9.3-7... (1,459 files, 17.9M)
Removing: /usr/local/Cellar/libgcrypt/1.7.0... (17 files, 1.5M)
Removing: /usr/local/Cellar/libgpg-error/1.21... (19 files, 419.4K)
Removing: /usr/local/Cellar/libksba/1.3.3... (13 files, 343K)
Removing: /usr/local/Cellar/mercurial/3.7.3... (386 files, 4.7M)
Removing: /usr/local/Cellar/node/6.0.0... (3,655 files, 38.8M)
Removing: /usr/local/Cellar/openssl/1.0.2g... (1,678 files, 12.0M)
Removing: /usr/local/Cellar/vim/7.4.1795... (1,687 files, 22.6M)
Removing: /Library/Caches/Homebrew/git-2.8.2.el_capitan.bottle.tar.gz... (11.2M)
Removing: /Library/Caches/Homebrew/imagemagick-6.9.3-7.el_capitan.bottle.tar.gz... (7M)
Removing: /Library/Caches/Homebrew/libgcrypt-1.7.0.el_capitan.bottle.tar.gz... (565.4K)
Removing: /Library/Caches/Homebrew/libgpg-error-1.21.el_capitan.bottle.tar.gz... (130.8K)
Removing: /Library/Caches/Homebrew/libksba-1.3.3.el_capitan.bottle.tar.gz... (126.6K)
Removing: /Library/Caches/Homebrew/node-6.0.0.el_capitan.bottle.tar.gz... (10.9M)
Removing: /Library/Caches/Homebrew/openssl-1.0.2g.el_capitan.bottle.tar.gz... (3.6M)
Removing: /Library/Caches/Homebrew/vim-7.4.1795.tar.gz... (12.0M)
==&gt; This operation has freed approximately 196.4M of disk space.


I have a Monday morning regimen of:

brew update
brew upgrade
brew cleanup


That brings me up to date on Homebrew, then all of my installed brews and then it frees up disk space by removing old brews that are no longer referenced. For brews that I need to keep at a specific version, I use brew pin to hold them there so I can still run this simple, three command, chain to update everything else around the pinned packages.