Mac OS Deleted

This process will Wipe Everything including the Bootcamp. If prepared for this - How to Create a Bootable Installer. Be sure to open the link in this page with Safari and any links in following page Also Only In Safari.

Once it is created, shutdown the target computer and disconnect all external drives. Connect the Installer and restart Immediately hold Option key. This loads the Boot Manager and choose the Installer Drive. It will present various options >> choose Utilities >> View All connected devices. Choose the Upper Most Drive usually named Apple HD or Apple SSD. In right panel, Tool Bar click Partition and when presented choose Single Partition. Let it do its work. Now Must Format the Drive and give it a Name. Below that choose HFS ( Journaled ) and below that Scheme: GUID Partition Map. In Tool Bar now choose Erase. Once done, back out of Disk Utilities and Choose Install macOS.

It will depend on just how old the machine is. Some older machines can boot from Internet Recovery Mode and if too old . . will require access to another machine to create a Bootable Installer.

Understand, Apple will offer to Install the most up-to-date version of macOS compatible with this computer if choosing this method

It one wants to try Internet Recovery Mode, shutdown and disconnect all external drives. Connect to Router via Ethernet cable if not that way move computer as close the Router as possible. Disconnect all others devices sharing the Wifi for the duration of this time. Restart computer and immediately hold Command + Option + r ( All three at the same time. ) One must create an Internet connection, so if via Wifi must input Wifi Password to make connection. Depending on ISP Speed and how bust Apple Servers are, a Globe will load. This will take some time until it eventually loads ( Much like Recovery Mode )

It will present several options and one must decide to 1 - Wipe the Drive - everything including Windows. This would mean choosing Disk Utilities >> View >> Show All connected devices. In this view on left side choose Upper Most Drive usually called Apple HD of Apple SSD. On right panel choose Erase and choose a name of it, below that choose Format HFS Journaled and below that Scheme: GUID Partition Map >> Erase. Once finished back out of Disk Utilities and choose Install macOS. Understand, Apple will offer to Install the most up-to-date version of macOS compatible with this computer. It will download and install and prompt to restart perhaps more than once - Normal. Once it finishes the final reboot will load the macOS and present the Setup Assist.

Done and enjoy

The error presented is because there was No Internet connection. Suggestion - shutdown computer and disconnect all external drives. Move computer as close to Access Point / Router as possible. Disconnect ALL other devices using the Access Point / Router. Connect MBA to charger. Start up in Internet Recovery and make sure to be watchful for the Wifi Icon and connect to it. This will require the User to manually input the Wifi Password to establish a connection. Only then will the Globe start to load only as fast as the ISP speed and Apple Servers at that time.

Once the Globe is fully loaded It will present several options and one must decide to 1 - Wipe the Drive - everything including Windows. This would mean choosing Disk Utilities >> View >> Show All connected devices. In this view on left side choose Upper Most Drive usually called Apple HD of Apple SSD. On right panel choose Erase and choose a name of it, below that choose Format HFS Journaled and below that Scheme: GUID Partition Map >> Erase. Once finished back out of Disk Utilities and choose Install macOS. Understand, Apple will offer to Install the most up-to-date version of macOS compatible with this computer. It will download and install and prompt to restart perhaps more than once - Normal. Once it finishes the final reboot will load the macOS and present the Setup Assist.

Done and enjoy