Disk Utility will not allow me to remove partition El Capitan 10.11.1

OK, I have an old MacBookPro5,3 running 8GB RAM and a 500GB upgraded SSD. This was my old machine, and I gave it to my daughter three years ago... I have now upgraded a second time and wanted to clean hers up a bit.

The machine is running fine, but when I configured it for her in 2013, I partitioned it (I think it was Mavericks at the time) with a Bootcamp partition and Windows7. She hasn't used Windows in a very long time on this machine, so having filled up the drive, I wanted to wipe out the Bootcamp partition and just make it all Mac again.

So I opened Disk Utility and tried to remove the Windows partition... but the Partition option in Disk Utility removed the partition (from 2 to 1 using the "-" command), but did NOT restore the additional empty space to the main drive portion!

How can I re-join the remaining portion of the drive?! Disk Utility sees only one partition, but on the desktop (and in the Disk Utility Menu) I still see two partitions!