MacOs Big Sur
How do I change my admin password on my MacBook if I forgot it?
MacBook Air 13″, macOS 11.3
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Change or reset the password of a macOS user account - http://support.apple.com/HT202860 - "You can change the password that you use to log in to your Mac, or reset the password if you don't remember it."
If you have another admin account set up on your MacBook, you can reset your password from there. If not, you may be able to reset it using your Apple ID or FileVault if enabled.