No disk when trying to reinstall mac

I'm using Macbook Retina Yosemite the latest model.

I'm trying to reinstall my OS X Yosemite but is running into issues.

I believe I accidentally deleted my Macintosh HD partition, which is causing no disk to be found except for a locked Recovery HD when I am trying to reinstall OS X:

My disk utility (I enabled debug mode, thus it shows hidden partitions) now looks like this:

I have no way to create a new partition on Macintosh HD as everything is greyed out.