@RIO is correct, if the prompt for the password occurs immediately when powering-on the computer.
If the prompt is later, namely at the "Windows Logon" screen, then please reply, to get a method for "blanking-out" that password.
There's a third possibility for a password prompt. It typically only shows up when a "scammer" was given full "remote-access" to the computer, and then set this password, and then issued a "ransom" demand to the previous owner -- "pay me 0.5 BitCoin, if you want me to give you that password".
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