In that case, I would recommend that you get hold of EasyBCD
and use it to set up a boot menu that will be using the Windows 7 boot loader. Once you have tested that it is working OK you can just reformat the Ubuntu partition.
Within EasyBCD ("Useful Utilities") there is a link to a site where you can buy Windows 7 boot CDs for $10. This might be a wise investement if you don't have system disks to allow you to repair simple problems. I've never tried them, so can't give a personal recommendation; it's just something that I noticed.
EasyBCD is a very useful (free) program and it's worth having a copy on any Windows 7 setup. And. no, I have no connection with NeoSmart other than as a satisfied user.