Password
I bought a Mac mini from a yard sale & can't get passed the password. How do I get passed it?
Question marked as
Contact the original owner and have them follow the directions @ What to do before you sell, give away, or trade in your Mac - Apple Support
Take it and a valid sales receipt from the owner to your local Apple Store or AASP and have them reset it for you.
Use it as a paper weight or door stop.
Return it.