Removing an overlay using green screen footage?
What you are looking for is called "Chroma Keying".

It works by sampling a color (in either 2D or 3D space, but you don't have to worry about that) and it, simply put, exchanges that color with the alpha channel - thus making the hue transparent. If you're working with Streamlabs OBS, regular OBS, After Effects or something similar, Chroma Keying is built into these programs. For a good result and knowledge about screen mattes, despill and other things to keep in mind while keying, check out the tutorials by andrew kramer.