"Disk Locked" macOS reinstall!
You have to create a new volume prior re-installing OS X. Otherwise you can’t select your drive.




Select Disk Utility from the utilities window of macOS Recovery, then click Continue.
Select your harddrive in the sidebar
Click the Erase button (MAKE SURE YOU DO HAVE BACKUP)
Format: Choose Mac OS Extended (Journaled)
Scheme: Choose GUID Partition Map.
Go back to the OS X installation guide.