Lightmap preview windows populate my screen at startup.

So when opening up Unity, I recently been working on polishing lightmaps and using the preview function. I have also been switching between different projects, closing Unity and opening up another version at times. Each time I open up Unity 2018.4.18f1 and the main project I am doing the last bit of polish on, the preview window opens up enough windows for it to cause actual problems. I think I had over 200 windows open up the other day. Can I get rid of them somehow, without the tedious process of having to close them one by one?

I'm working on a macbook pro.