As on operating systems Windows, formatting the entire hard disk, either classic HDD or SSD, cannot be done with the operating system turned on. It is also normal. It would not even be able to delete system files while it was running.
Format the entire disk to Mac, is done using utility programs from Recovery Mode. These tools are available regardless of the condition of the hard drive. For example, when you change the HDD or SSD to Mac, entering Recovery Mode is required to create the partition and install the operating system. It is equally necessary to start one Mac in Recovery Mode and when we want to completely erase the disk space and reinstall the operating system.
How to open a Mac in Recovery Mode / macOS Recovery
There are three ways we can start one Mac in Recovery Mode, or macOS Recovery, as it is also known. Each variant will open the same utility, but it will be different operating system to be installed.
Stop everything Macthen press the power button. Immediate press and hold the key combinations below, depending on the version of macOS you want to install.
Command (⌘)-R : You can reinstall the latest version of macOS present on Mac.
Option-⌘-R : You do upgrade to the latest version of macOS compatible with MacYour CPC
Shift-Option-⌘-R : Install version of macOS with which the device came from the factory. If that version is no longer available, the nearest version will be installed.
How to format / delete all data on a hard drive Mac
Of course, before this process you must Have a backup copy of all your data. These will be eradicated.
from macOS Utilities, we go and open disk Utility.
In disk Utility, we click on “View”→“Show All Devices". The option is in the upper left corner.
Select the physical hard disk you are going to format - it is in the tree above all partitions or volumes. Click “EraseFrom the top of the Disk Utility, then give up a name main partition, choose formatting si hard schemeacquis.
An option box will open. For the first layout, it is advisable to choose the formatting: “Mac OS Extended (Journaled)". In the case of SSDs, the partition of the first container will automatically become APFS volume.
Click Erase and wait for the operation to complete. Click "Done" the final.
After this operation, the hard disk will be empty and you will have to reinstall the operating system. Close Disk Utility and go to "Reinstall macOS".How to format / delete all data on a disk (HDD or SSD) on macOS