re expand a partitioned disk
To delete CoreStorage volumes you have to use the CLI:


please backup your volume "mainHD"
boot to Internet Recovery Mode (hit altcmdR immediately after the start-up chime)
open Disk Utility and check/repair mainHD
quit Disk Utility , open in the menubar Utilities/Terminal.app and enter diskutil cs deleteVolume LVUUID to delete the Logical Volume
in your case: diskutil cs deleteVolume B3E1FCD6-ACAB-4152-AEB5-71F41C329C17
and then
diskutil cs delete LVGUUID to delete the Logical Volume Group
in your case: diskutil cs delete C2BDDBCA-73CF-473C-B9DA-E5682EF29610. Your LGV will be converted to a simple, empty volume with the name "Untitled".
enter diskutil list and sudo gpt -r -vvv show -l /dev/disk0
result of the latter (start blocks and block sizes differ because the example disk is half as big as yours &amp; some parts of the output are omitted):

...
         40       409600      1  GPT part - "EFI System Partition"
     409640    244763224      2  GPT part - "mainHD"
  245172864      1269536      3  GPT part - "Recovery HD"
  246442400    242522776      4  GPT part - "Untitled"
  488965176      1269536      5  GPT part - "Recovery HD"
...  

enter diskutil unmountDisk /dev/disk0
then remove any partition except those with index 1 and 2 (EFI and mainHD) with  sudo gpt remove -i IndexNumber disk0
enter diskutil resizeVolume disk0s2 0b to expand it to the full size.
enter exit and quit Terminal
open Disk Utility, check/repair mainHD again and quit afterwards
reboot to main HD
rebuild Recovery HD with Recovery Partition Creator 3.8 or by just reinstalling Mavericks 10.9.5 (don't use 10.9.4 or earlier!). Your data and apps will be preserved.