Uninstalling PyGTK from macpkg on Mac OS X
Find the BOM file in ~/Library/Receipts or /Library/Receipts
refer this article you can uninstall a pkg easily http://hints.macworld.com/article.php?story=20100107090139622

if you can not find that, download the .pkg file again if you already delete

following these steps you can see what and where all the files install by this pkg


put the .pkg into temporary directory, /tmp e.g.
cp XZ.pkg /tmp  for example, "XZ" is the .pkg filename
cd /tmp
expand the pkg file
pkgutil --expand XZ.pkg /tmp/XZpackage
Go ahead and cd in the directory 
cd /tmp/XZpackage
go into the directory XZ.pkg or local.pkg
cd local.pkg
list the install files
lsbom Bom


PS: simply you can use the Pacifist, this App will show you the result