How to fix an accidentally created Apple CoreStorage Volume, LVG, Logical Volume Group (broken partitions)
The following should work:


Open Terminal and enter:

diskutil list
diskutil cs list

Verify (and repair) the volume if necessary:

diskutil verifyVolume disk0s2


If a repair is required boot to Recovery Mode and repair the main OS X volume.
Delete the Logical Volume Group

diskutil cs delete 28A99931-20D1-4D0C-8B5A-9872BC7270E2


This should convert the LVG LINUX to a normal partition
Then enter diskutil list again and erase the 134 MB and the 1.3 TB partition (use the proper disk identifiers found in your listing above here):

diskutil eraseVolume Free Space disk0s5
diskutil eraseVolume Free Space disk0s4

Verify the volume again:

diskutil verifyVolume disk0s2

Check the limits of disk0s2

diskutil resizeVolume disk0s2 limits


This will output something like that:

For device disk0s2 iMac HD:
    Current size:  1.4 TB (1396811730944 Bytes)
    Minimum size:  ? 
    Maximum size:  ?

Try to expand the main volume - you can't expand the volume beyond the limit shown in the previous output

 diskutil resizeVolume disk0s2 R


If the R size option fails try to use a real size like 3999g or a percentage 100% (on some external disks this may fail because of some 2 TiB limit).

 diskutil resizeVolume disk0s2 3999927271424b


or

 diskutil resizeVolume disk0s2 100%