This is a making of my own stupidity. As I mess around with my dev environment a lot I occasionally wipeout my laptop to restart with a cleaner env. This time I think I accidentally removed one too many partitions and didn't bother with making a backup ( :S ). I tried following the answer for this similar question https://apple.stackexchange.com/questions/250427/cant-reinstall-mac-os-x-el-capitan-because-the-only-partition-is-a-locked-os-x to no avail as the images will show below. In addition to those, things like gpt create -f disk0 returns unable to open device 'disk0' : Resource busy.
1 Answer
It uh..fixed itself... Previous restarts had the same results as above. But another restart did the trick to allow disk unmounting :S