Boot into the Windows 7 that's on your SSD.
Now go into Disk Management and re-format the HDD partition that contains the other (unwanted) Windows 7: Control Panel > Admin Tools > Computer Management > Disk Management
Right-click the HDD partition and choose "Format".
Wait for the format to complete.
Now still in Windows, click Start > Run.
Type msconfig & press <Enter>.
Under the "Boot" tab, highlight the now redundant line and click "Delete", then click 'OK'