The easiest way to remove an entry in the Windows 7 Boot Configuration is to use msconfig.
To launch msconfig:
1. Click Start
2. In the Search text box, type msconfig
3. Launch msconfig by selecting it from the search results above the search text box.
After msconfig is launched:
1. Go to the Boot tab
2. Slect the boot entry you want to delete.
3. Click the Delete button and then click OK.
Make sure to be logged in to the Windows 7 partition you want to keep when performing these steps so you don't delete the good installation by mistake.