If it's not there then there are a couple of possibilities.
1. You "installed" it by simply unzipping it into a directory tree without changing the registry. I have several programs on my computer like that and they are the simplest to remove, simply delete the entire directory tree.
2. The program was installed but somehow either the registry never recorded it or was corrupted; or you already removed it using the add/remove programs and what you are seeing is some left over stuff.
Can you give a few more details?