I deleted the Macintosh hd drive in my MacBook Air and cannot reinstall the ox s
Can I download OS X El Capitan from a different computer to install to my MacBook Air
MacBook Air 13", OS X 10.10
What do you mean by "deleted the Macintosh hd"? "Macintosh HD" is just one volume on the internal hard drive. If it is just that you have deleted then the recovery partition should still be there. Of course if you've wiped the whole physical drive all volumes will have gone. Have you tried booting into recovery mode?
If you can't boot into recovery mode but you have downloaded El Capitan from App Store before then it should appear in "Purchased" if you sign in to App Store with the same Apple ID on another Mac. You should then be able to make a bootable external drive for the re-install.
If you've never downloaded it before then I think it can only be downloaded on an old Mac which doesn't support anything later than El Capitan.