How can I turn off light in compositing nodes? I want to animate this neon light to be complete turned off but it still shows some light after I put zero on everything, what can I do?

I basiclly explain everything in this picture.

Thanks. And sorry for my English.
When I followed the tutorial, I needed to deselect Ambient Occlusion in the World tab in order to make everything black.


Also, in the compositing nodes, I forgot to connect the image to the second mix node, and that caused my lower text to always appear.