brew bundle dump
brew bundle --force cleanup
#######
### brew now supports Brewfiles.
### brew bundle dump generates a Brewfile with all the packages installed by user.
### This file can be used to install the same software automatically.
### But also for doing a cleanup of unused packages.
### Edit the file then keep only the packages you need.
### Then run:
brew bundle --force cleanup
#######
### It will remove everything not listed or depending on the packages in the file.