Follow the steps on Apple’s How to create a bootable installer for macOS – Apple Support webpage to download the macOS Big Sur app and create bootable media. You must use the Safari browser.
Boot a Mac from a Bootable Drive (Intel processor)
- Connect the boot media device to the Mac
- Press and hold down the Option Key during boot, until a screen showing bootable volumes is displayed
- Select the volume containing the bootable installer and press Return.
- If prompted, enter the local admin account credentials to unlock the disk and open the macOS Utilities page
Option 1: For computers previously managed by Centrify, a clean wipe of the drive using Terminal is highly recommended:
- From the Utilities menu, select Terminal
- Type: diskutil list in the terminal window and press the Return key.
- Scan the output and find the apfs container, and note the IDENTIFIER
- In the below example, IDENTIFIER is “/dev/disk1s2”
- Type: diskutil apfs deleteContainer /dev/disk1s2 and press the Return key
- After the operation completes, quit Terminal
- In macOS Utilities, double click on Disk Utility and change the name of the drive from Untitled to Macintosh HD
- Select Erase and Format APFS. Click Done when formatting is complete
Option 2: For computers that do not require a clean wipe, use the following steps to erase and format the internal drive:
- In macOS Utilities, double click on Disk Utility
- Select the internal drive (typically named Macintosh HD) and click the Erase button using the following options:
- Name: Macintosh HDFormat: APFS
- When erasing is complete, close Disk Utility.
When the disk is prepped following either Option 1 or Option 2 above, click Install macOS in the Utilities page and follow the on-screen prompts to finish installation of the macOS Big Sur.