Erase and reformat a storage device in Disk Utility on Mac

In Disk Utility on Mac, you can erase and reformat storage devices to use with your Mac. Erasing a storage device deletes everything on it.

Important: If you have any files you want to save, copy them to another storage device before erasing a device.

1. Access the Disk Utility application on your Mac through one of the following methods, depending on the type of disk or volume you wish to erase:
   • To erase your startup disk:  Boot your computer into macOS Recovery, then select Disk Utility from the Recovery application. For instructions on how to boot your computer into macOS Recovery, please refer to  Intro to macOS Recovery.

     
     Note:  If you intend to prepare your Mac for trade-in, sale, or donation, and your device is a Mac with Apple silicon or an Intel-based Mac equipped with an Apple T2 Security Chip, please utilize  Erase Assistant.

   • To erase any other type of storage device:  Double-click Disk Utility located in the /Applications/Utilities folder.
     
     
2. Select View  > Show All Devices.
   
   
3. In the sidebar, select the storage device you wish to erase, then click  .
   
   

4. Click the Scheme pop-up menu, then select GUID Partition Map.

   If the Scheme pop-up menu is not accessible, ensure that you have selected the storage device you wish to erase, which is located at the top of the hierarchy.
   
   

5. Click the Format pop-up menu, then  select a file system format.
   
   
6. Enter a name for the storage device.
   
   

7. (Optional) If available, click Security Options, use the slider to determine the number of times to overwrite the erased data, then click OK.

   Secure erase options are available only for certain types of storage devices. If the Security Options button is not present, Disk Utility is unable to execute a secure erase on the selected storage device.
   
   

8. Click Erase, then click Done.