CCleaner free equivalent on OS X?
If you are going to re-partition to install another O/S then a cleaner won't do much, it really depends on how much room you need to recover for your partition.

That said there are a number of cleaners out there. I have always used the free Onyx. I usually get it off of MacUpdate. Note that the latest version is always for the latest O/S if you don't have Mavericks look on the developer's website for earlier versions.

http://www.macupdate.com/app/mac/11582/onyx

Oddly enough CCCleaner is available for the Mac, and while I have used the PC version quite a bit I have never used it on the Mac, preferring to stick with the utility I know. So I can't speak to how good a job CCCleaner does on the Mac.

MacUpdate is a great place to look for software, pretty much everything you are looking for here can be found there.