My Macbook has about 15gb of .pkg files from previous versions of OSX. Is there anyway to safely remove them?
Once you have used the .pkg to install the apps you should be able to just throw them.
If you are twitchy about this then just transfer them to a different drive and see if anything stops working before you finally throw them, but it should be fine if you did any install correctly.
There's no option to delete them. I'm suprised OSX doesn't clean them up with the subsequent install, but I've accumulated packages from the last 3 updates.
Drag them into Trash.
This is strange. There shouldn't be any 'leftover' pkg files, and there shouldn't be anything stopping you deleting them. I would be worried they are some form of Malware.
You could try navigating to the folder in a terminal window and type (no quotes)
'sudo rm *.pkg'
They can't be dragged in to the trash.