OK. The first thing to do is to make sure that you know which menu entry is the one that you want to delete. Do they read the same or are they worded differently? If they are worded the same then I would suggest that you wait for the menu to time out (should take 30 seconds) and make sure that the computer boots into Windows 7. This means that the default boot entry is the correct one.
Now download the program EasyBCD
and install it. (There are other ways of editing the boot menu, but this is the safest.) This program has an option "Add/Remove entries" that will let you edit the boot menu to remove the unwanted option. You might want to "Check Settings" first to make sure that you are removing the correct entry. They will be listed in the same order that they appear on the boot screen. Assuming that Windows is installed on the C: drive this is the entry that you want to keep.