How can I unlock my MacBook if I don’t remember the password?

You should read this article for guidance on how to reset/recover the login passcode

If you forgot your Mac login password - Apple Support

"How can I unlock my MacBook if I don’t remember the password?: I don’t remember the password to open my MacBook"

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Troubleshooting a Locked Mac Account:

Hold it Right There!:

Enter the passcode incorrectly too many times, and you'd likely be locked out for good. So, hold it right there, and wait out the time allotted. The password would be the one you've always entered. If you do not know it, then look for it in a location you may have stored it in.

When Allowed to Proceed:

Reset this Using the Login Screen: Make the change with the link provided by @I-Am-Smart

Having Issues? Go Here: If you can't Reset your Mac Login Password - Apple Support