It seems this guy has the same problem as you:
Post 24
http://forums.totalwar.org/vb/showthread.php?t=63661
Meaning you have to uninstall it manually.
However I found this patch that addresses one uninstall issue with the demo. But it doesn't mention your exact problem. You could try it though as they could be related:
http://www.fileshack.com/file.x/1071...ord+Demo+Patch
Good luck!
