The installer uses a shared bundle pool kept in ~/.p2/pool by default; you can change it via the menu. But you said you unzipped packages. The rest of what's on ~/.p2 is generally just a few caches that I don't imagine should take so much space. What is taking up so much space in your ~/.p2 folder?
As long as you don't have a pool in there then it's basically only p2 caches, so deleting is okay, but it will force p2 to refetch the cached things the next time, making it slower, and they'll come back again as well.