Option 1: Change Windows Password from Command Prompt

1. Open an elevated Command Prompt. Click on Start button, go to All Programs ->Accessories and right click on Command Prompt and select "Run as Administrator" from context menu. In Windows 8, you can do this by simply pressing Windows Key + X + A.
2. You can use the net user command to change Windows password easily, without supplying the old password:

   net user username  new_password

   Replace username with your Windows account name, and new_password with your desired new password.
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