You can find homebrew uninstall info from here

https://github.com/Homebrew/brew/blob/master/share/doc/homeb...

  # I did:
  
  # remove all packages
  $ for f in $(brew list); do brew remove "$f"; done
  
  # download uninstall script
  $ curl -O https://raw.githubusercontent.com/Homebrew/install/master/uninstall
  # review script
  # run uninstall script
  $ chmod +x uninstall
  $ ./uninstall
  ...
  
  # review
  /usr/local/bin/
  /usr/local/etc/
  /usr/local/lib/
  /usr/local/share/
  
  # I removed
  $ rm -rf /usr/local/share/ /usr/local/etc/
  
  # Restore permissions
  
  $ sudo chmod 0755 /usr/local
  $ sudo chgrp wheel /usr/local