You can use a firmware password as a security measure to make sure your Mac can only start up from your startup disk.
Only Apple Retail Stores or Apple Authorized Service Providers can unlock computers protected by a firmware password if you can't remember the firmware password you set.
If you forget your firmware password, schedule a service appointment with an Apple Retail Store or Apple Authorized Service Provider. If you plan to visit an Apple Retail Store, make a reservation (available only in some countries and regions). Bring your proof of purchase (original receipt or invoice) with you.
These Mac computers can use firmware passwords:
- MacBook Air (Late 2010) and later
- MacBook Pro (Early 2011) and later
- MacBook Pro with Retina display (all models)
- iMac (Mid 2011) and later
- Mac mini (Mid 2011) and later
- Mac Pro (Late 2013)
- MacBook (Retina, 12-inch, Early 2015) and later