If you have forgotten your Mac’s login Password, reset your Password following steps as below:
Boot up your Mac with holding down Command+S key combination, to enter single-user mode;
Run command: mount –uw /
Run command: rm /var/db/.AppleSetupDone
Run command shutdown –h now
Password is deleted now, boot up your Mac to setup your Mac;
If you have set your Master Password and forgotten, also you have not turned on FileVault (and therefore you have no material encrypted by FileVault), then you can reset your Master Password following steps as below:
Boot up your Mac with holding down Command+S key combination, to enter single-user mode;
Run command: mount –uw /
Run command: rm /Library/Keychains/FileVaultMaster.cer
Run command: rm /Library/Keychains/FileVaultMaster.keychain
Run command reboot;
