Change FileVault preferences on Mac
Use the FileVault pane of Security & Privacy preferences to protect the confidential information on your Mac. See How does FileVault encryption work?
To change these preferences on your Mac, choose Apple menu > System Preferences, click Security & Privacy, then click FileVault.
Note: If the lock at the bottom left of the pane is locked , click it to unlock the preference pane.
Turn On FileVault
Click to securely encrypt all the information currently on the startup disk, and encrypt and decrypt new information as it is read and written to storage. The initial encryption may take a while, depending on the amount of data that is stored, but you can use your Mac while encryption is taking place.
When you turn on encryption, all users are required to use a login password. When you first turn on FileVault, you choose how you want to unlock your startup disk if you forget your login password: using your iCloud account and password, or using a recovery key that’s created for you. If you choose the recovery key, you must write down and keep track of the recovery key yourself. You can also add other users who are allowed to unlock and access the information on your Mac.
Turn Off FileVault
Click to decrypt the encrypted information on your Mac and stop encrypting new information.
Click to allow users to log in at startup and unlock the encrypted information on the Mac. Users that are not enabled need an administrator to log in before they can use the Mac.