Be very careful if using nail polish remover. It can damage paintwork.
If solvents fail to shift it it may be scratched. Toothpaste can work ,but will probably need a lot of hard work, preferably with a rotary mop. (Not a toothbrush
) I'd test it on a small area out of drivers line of sight. Best to be very critical of results. The slightest imperfection could ruin vision.
You can buy DIY screen scratch removal kits ,with abrasives etc. I havnt checked the prices but you might find it wont be much more expensive having it done expertly by a windcreen company. (except they may tell you it needs replacing when it may not .)