I had the same problem. This is just a Menu that in some point you putted there.
To check it out, open your 'Guide.fig', and then click on the Object Browser as shown in the image and you'll be able to see all your controls and stuff. In my case, the Menu (Untitled 1) appears at the end. I wasn't able to delete it but you can make it 'no visible'. To do so, double click on the 'Menu' and the Inspector will appear so you can uncheck the 'Visible' property.