Q: How to delete "Free Space" Partition?
I partitioned my MacBook Pro into 2 volumes so I could dual boot Mavericks and Yosemite Developer Preview. After testing Yosemite, I found out that it was stable enough to run on my main partition. I installed it on my main partition replacing Mavericks and deleted the second partition which included Yosemite. While deleting, somehow I was left with an empty partition called "Free Space" which I cannot delete. 
I am pretty sure the problem isn't related to Yosemite being a developer preview as it could've happened under an previous stable OS. How can I merge my "Free Space" partition with Macintosh HD?
MacBook Pro with Retina display 13-inch Late 2013
2.8GHz Intel Core i7
16GB RAM
Intel Iris graphics
512GB SSD
OS X Yosemite Developer Preview 2
Posted on Jun 24, 2014 3:12 AM
I had the same problem as well. I went to system preferences and turned off FileVault under security and privacy. Then I restarted my mac in recovery mode,OS X: About OS X Recovery - Apple Support. Selected my mac drive and the partition tab and I was able to resize my main drive. I found this on some other mac forum, hope this help.
Posted on Dec 17, 2015 9:24 PM