Resetting Macbook 2012 for sale

Using disk utility I deleted 'Mackintosh HD' from the left hand toolbar list of volumes.

The instructions said to delete (using -) any other volumes shown so I deleted again - then noticed the instructions said in italics to ignore other volumes called Mackintosh but it was too late!

Now through recovery I need to reload OS X Yosemite but it says select the disk that you want to install OS X but there is no disk shown, just a circle with a full X across it.

What can I do to install OS X?????

Thanks