how to delete files that .pkg installs on your machine...

pkg_to_delete.sh

# ${original.pkg} => the original name of .pkg file
pkgutil --expand ${original.pkg} expanded.pkg

# to find what Bom files you got
find gviz.pkg -name 'Bom'

# to show the files and directories
find gviz.pkg -name 'Bom' | xargs -I{} lsbom {}

# lsbom exports "tab delimited file".  And also it's on relative path.
# but once you can get a list of files you want to delete, 

cat deleting.list | xargs -I{} rm -rf {}