“Unlinked kegs in your Cellar”. How do I remove them?

Question

After installing and uninstalling some programs through brew and brew cask, now I get brew doctor saying \"unlinked kegs in your Cellar\".

Answer 1

brew 1.9.0

brew cleanup [options] [formula|cask]

Remove stale lock files and outdated downloads for all formulae and casks, and remove old versions of installed formulae. If arguments are specified, only do this for the given formulae and casks.

   --prune                      Remove all cache files older than specified
                                 days.
-n, --dry-run                    Show what would be removed, but do not
                                 actually remove anything.
-s                               Scrub the cache, including downloads for
                                 even the latest versions. Note downloads
                                 for any installed formula or cask will
                                 still not be deleted. If you want to delete
                                 those too: rm -rf "$(brew --cache)"
    --prune-prefix               Only prune the symlinks and directories
                                 from the prefix and remove no other files.
-v, --verbose                    Make some output more verbose.
-d, --debug                      Display any debugging information.
-h, --help                       Show this message.

Older versions

brew prune [--dry-run]: Remove dead symlinks from the Homebrew prefix. This is generally not needed, but can be useful when doing DIY installations. Also remove broken app symlinks from /Applications and ~/Applications that were previously created by brew linkapps.

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