OS X Partition not resizable
Solution 1:
Boot into Recovery HD, open Disk Utility. Choose Yo Drive in the list and select the Restore tab. Make Yo Drive the Source and Macintosh HD the Destination. This will erase all content on Macintosh HD and replace it with the contents of Yo Drive. Back up anything important on Yo Drive before hand in case of failure during the restore. After that you should be able to erase the second partition and extend to take up the whole drive.