There is a seam ripper and thread remover/puller that you can buy. It is essentially a seam ripper, that I am sure you already have, with an eraser!
So, why not just use an eraser, that you probably already have. I use Staedtler Mars 52650 Plastic Eraser.
I don't know what the material is on the purchased thread remover but, I know that my eraser works pretty well. I also cut the eraser down a bit and put the smaller bits under the back feet of my sewing machine to tilt it toward me. This makes it easier to see when I am sewing.
