If you have a bootable CD/USB drive,some password tools can be burn to it and you can boot your computer from USB to run the software,so that you can recover/remove Windows 7 password from USB.
Such as Daos Windows 7 Password Recovery Tool,here I just list the simple steps:
Step 1: Download Daos Windows 7 Password Recovery Tool/Windows Password Rescuer
Step 2: Run it to burn to bootable CD/DVD or USB flash drive
Step 3: BIOS setting of your locked computer to boot form CD or USB
Step 4: Reset Windows 7 password on a friendly window after "Daos Windows 7 Password Recovery Tool" starts.You also can use Daos Windows 7 Password Recovery Tool to add a new user with administrator privilege to your Windows. With this New user account you can logon your locked computer directly. http://www.daossoft.com/windows-7-password-recovery/how-to-use-windows-7-password-recovery-tool.html