Cannot restore Macbook to single partition

I created a second partition on my Macbook Pro for a second operating system; howevr, now I would like to restore my Macbook back to using the whole disk for OS X (Mavericks).

I booted into Recovery Mode, and launched Disk Utility, but I cannot remove either partition, nor can I change the partition layout. Currently, the first partition is a blank Mac OS Extended (Journaled) filesystem, and the second partition is just "free space". I tried formatting it, but when I click apply, nothing happens. If I try to quit Disk Utility at this point, it tells me I have unsaved changes.

Can someone explain where I'm going wrong?