Click 'Yes' in the warning window appears to continue. Enter the Partition label, select the target file system, and set the cluster size, then click 'OK.' Step 3.

If you want your Mac to start up again from the volume you just you erased, select Reinstall macOS in the utilities window, then click Continue and follow the onscreen instructions. Navigate to the 'Disk Manager' and then right-click the first partition and choose 'Format.' Step 2. Step 2: Right click on the icon of your portable hard drive and choose 'Format Partition' in the drop-down menu.

When done, quit Disk Utility to return to the utilities window.

Optional: If you previously used Disk Utility to add internal volumes other than Macintosh HD, you can erase them individually using the same process.

If this button isn't shown, click Erase instead.

Format: APFS or Mac OS Extended (Journaled), as recommended by Disk Utility.

Click the Erase button in the toolbar, then enter the requested details:.

Select Macintosh HD in the sidebar of Disk Utility.

From the utilities window, select Disk Utility and click Continue.

If asked, select a user you know the password for, then enter their administrator password.Press Command + Space keys to open Spotlight, type: terminal, and hit Return. Keep the new hard drive to your Mac computer via a connection cable.

Select an admin user and type in their password. Start up from macOS Recovery: Turn on your Mac, then immediately press and hold these two keys until you see an Apple logo or other image: Command (⌘) and R. Format Disk on Mac Using Terminal Step 1. Boot your Mac in Recovery mode by holding down Command and R until you see the Apple logo or other image. Immediately after the startup sound, press and hold the C key to start up from CD. Press and hold Command + R to start the Mac in Recovery mode.

Reformat hard disk for mac