How to completely remove Ubuntu?

I installed Ubuntu using Wubi installer, but I couldnt boot to it. So I uninstalled it on the Control Panel. Then I tried the full installation wherein it boots to the Ubuntu environment. After installing Ubuntu there, I couldnt boot to my Windows 7 anymore! So in an attempt to salvage the whole thing, I inserted the Ubuntu CD again and chose Erase Ubuntu and Reinstall. (I was wondering, why wasn't there an option to just "Erase Ubuntu"?) I did that though, and I got my Windows 7 back. But upon checking my drives via the "Create your own partition scheme" (not sure if it's the exact words) I saw that one of my partitions still has Ubuntu on it, and there's no way I can delete it if I don't overwrite another Ubuntu! I can't access that partition on windows 7 either! Need help!

I think your problem is only about the partition. Linux use ext2/3 file system and Windows doesn't support that file system, so normally you cannot see the drive which format in ext2/3 on Windows. My suggestion here is you can use PartitionMagic (or any tool works with partition), erase that drive and merge it to another fat32/ntfs drive, so you can retrieve it completely