Restore Macintosh HD to its original partition configuration
There is no need to delete the CoreStorage Logical Volume Group. Just resize it:


Have a backup!
Reboot into Internet Recovery Mode (hold Option-Command-R) as the machine is restarting).  You'll eventually be presented with a Max OS X Utilities window.


In the menu bar along the top of the screen, click Utilities -> Terminal.


At the prompt, enter diskutil cs list and you should get output similar to the following.

CoreStorage logical volume groups (1 found)
|
+-- Logical Volume Group 9B4FB14F-DA7D-46EF-BBB9-FD99166C1E2F
    =========================================================
    Name:         Macintosh HD
    Status:       Online
    Size:         920186970112 B (920.2 GB)
    Free Space:   49152 B (49.2 KB)
|
+-&lt; Physical Volume DE3C1DD4-3EA5-4484-AE40-C8BD60AD5F75
|   ----------------------------------------------------
|   Index:    0
|   Disk:     disk0s2
|   Status:   Online
|   Size:     120988852224 B (121.0 GB)
|
+-&lt; Physical Volume E1C56E99-3ED2-437F-AED0-A454FCC4E983
|   ----------------------------------------------------
|   Index:    1
|   Disk:     disk1s2
|   Status:   Online
|   Size:     799198117888 B (799.2 GB)
|
+-&gt; Logical Volume Family D824D426-8315-405A-A7CD-5B62E549FBAE
    ----------------------------------------------------------
    Encryption Status:       Unlocked
    Encryption Type:         None
    Conversion Status:       NoConversion
    Conversion Direction:    -none-
    Has Encrypted Extents:   No
    Fully Secure:            No
    Passphrase Required:     No
    |
    +-&gt; Logical Volume AC1A071B-63D0-488F-AFFF-D296E446FE6B
        ---------------------------------------------------
        Disk:                  disk2
        Status:                Online
        Size (Total):          914000052224 B (914.0 GB)
        Conversion Progress:   -none-
        Revertible:            No
        LV Name:               Macintosh HD
        Volume Name:           Macintosh HD
        Content Hint:          Apple_HFS`

Copy the Logical Volume (LV) alphanumeric UUID of your CoreStorage volume. The LVUUID should be the fourth (the fifth if you have a Fusion Drive) listed. In the above example the alphanumeric is:
AC1A071B-63D0-488F-AFFF-D296E446FE6B
Run the following command:  

diskutil cs resizeStack LVUUID partsize  


According to the number found above it would be:  

diskutil cs resizeStack AC1A071B-63D0-488F-AFFF-D296E446FE6B 0g  


This will expand your CoreStorage volume to full 1.24 TB
Quit Terminal.app and start Disk Utility and verify the expanded volume.