Hi I am trying to bring back to factory settings my mac air. I am in disk utility. I have erased a partition called Macintosh H, but it doesn't let me erase the rest of the disk.

Hi I am trying to bring back to factory settings my mac air. I am in disk utility. I have erased a partition called Macintosh H, but it doesn't let me erase the rest of the disk.

I am in Broadway Apple store but no genius at the bar for the last half an hour and besides I have been told they are all booked out for the day. The guy in open training said he can't help me with this technical issue. No one to one is available either.

What can I do from here?

😕