Step 1 - Boot into macOS Recovery Boot  (the steps will vary depending on your processor model)

for M1

shutdown the machine

Choose Apple menu  > Shut Down.

Press and hold the power button on your Mac until you see “Loading startup options.”

Click Options, then click Continue.

If requested, enter the password for an administrator account.

for Intel

shutdown the machine

power on and hold Cmd + R immediately when powering on the machine

Step 2 - Erase and reinstall macOS

If you erase and reinstall macOS, your user accounts, network settings, and all of the files and folders on your Mac are deleted. Before you erase macOS, back up any files you want to keep by copying them to another disk or storage device or cloud services like or similar.

While the screens change slightly over time the steps are generally the same

  1. Make sure you’re connected to the internet  (it will generally prompt you to do this as needed - use the top right wifi menu)
  2. In the Recovery app window, click Disk Utility, then click Continue.
  3. Select your disk (typically Macintosh HD) in the list on the left, then click the Erase button. 
  4. select the erase volume group button- or as needed Enter a name for your disk, choose APFS from the Format pop-up menu, then click Erase
  5. After the disk has been erased, choose Disk Utility > Quit Disk Utility.
  6. Select Reinstall macOS, click Continue, then follow the onscreen instructions.

How-to video (macOS Catalina 10.15.7):

If during the process you need assistance it would be helpful to call for live troubleshooting or as desired schedule a meeting