I don't know exactly what do you mean with "Remove Matte effect". (I'm only an occasional user to Premiere Pro.)
Is it: ------ On V1, I do have a picture (that with the fire/lightnings). I've resized the image, so that it fits the size of the clip on V2. When I move the Image in V1 underneath the clip(with the mask), I see the "fire" on(through) that black aera(you see on the screenshot), how I expected it.
Or do you mean: ---------------- something like "Drop the Luma Key onto the clip"?
what I did: ----------- I only used the opacity-mask, as shown in the picture. Nothing else.
when I remove that mask(matte? is matte a synonym for mask?), and make a new one, say a circle or a box, it is the same effect. the black area is offset to the blue mask-border.
It is possible to release the boy on the picture by pushing the vertices to the far right in a corresponding order but I think, that's not the idea of that tool?