Before you start

1. Connect the MacBook to power.
2. Back up any files you want to keep, for example, with Time Machine.
3. Make sure you know the Apple ID password used on this Mac.
4. Connect to Wi-Fi or Ethernet.
5. Sign out of iTunes. Open iTunes, from the menu bar at the top of your computer screen choose Account > Authorizations > Deauthorize This Computer. 
6. Turn off Find my Mac and sign out of iCloud. Choose Apple menu > System Preferences, click Apple ID, click iCloud in the sidebar, then deselect Find My Mac to remove your Mac. Then click Overview in the sidebar, then click Sign Out. Signing out of iCloud turns off all iCloud features on the device.
7. Sign out iMessages.  Launch the app. In the Messages menu bar, click on Preferences. Click the account you want to sign out in the left panel. Next to your Apple ID on the right click on Sign out.
8. Unpair Bluetooth  Go to the Apple menu > System Preferences and choose Bluetooth. Here you can unpair keyboards, headphones or other Bluetooth-enabled peripherals.

Method 1: Reset from macOS

1. Click the Apple menu in the top-left corner.
2. Open System Settings.
3. Go to General.
4. Click Transfer or Reset.
5. Click Erase All Content and Settings.
6. Enter the administrator password if asked.
7. Follow the on-screen instructions.
8. When asked, enter the Apple ID password to remove Activation Lock.
9. Confirm that you want to erase the Mac.
10. Wait until the Mac restarts and shows the setup screen.

The MacBook is now reset to factory settings and ready for a new setup.

Method 2: If macOS does not start

1. Shut down the Mac completely.
2. Press and hold the power button until you see Loading startup options.
3. Select Options, then click Continue.
4. Choose an administrator account and enter the password.
5. Open Disk Utility.
6. Select the internal startup disk, usually Macintosh HD.
7. Click Erase.
8. Use:
   • Name: Macintosh HD
   • Format: APFS
9. After erasing, quit Disk Utility.
10. Choose Reinstall macOS.
11. Follow the on-screen instructions.