Erase and reinstall macOS
Important: Do not follow the steps below if your computer is a Mac with Apple silicon or an Intel-based Mac with the Apple T2 Security Chip. Instead, follow the steps in Erase your Mac.
Before you begin
Erasing your Mac removes all the information from it. Back up your Mac with Time Machine.
Make sure your Mac is connected to the Internet.
If you’re reinstalling on a Mac laptop, plug in the power adapter.
Erase and reinstall macOS on an Intel-based Mac without the Apple T2 Security Chip
You can use macOS Recovery, the built-in recovery system on your Mac, to erase and reinstall macOS.
Choose Apple menu
In the Recovery app window, select Disk Utility, then click Continue.
In Disk Utility, select the volume you want to erase in the sidebar, then click Erase in the toolbar.
Type a name for the volume in the Name field, click the Format pop-up menu and choose APFS, then click Erase Volume Group.
When the erase process is complete, click Done, then choose Disk Utility > Quit Disk Utility.
In the Recovery app window, click Reinstall macOS [name], then click Continue.
Follow the onscreen instructions.
