If it doesn't affect the appearance too much, you'd better keep it. It may damage the surface coating of the kitchen ventilator or even cause corrosion if you tear it off. If you must remove it, do it in a gentle manner. Ways like heating with fire, scraping with knife or grinding should be chosen with caution because even if it's the glass, scratches may remain on it. You could try to use some oil to soak it but it takes time.
If it's stainless steel products, you can directly tear it off. But if it's sprayed, you must be careful, otherwise the whole paint film will be destroyed and the paint of kitchen ventilator will be easy to peel.
Heat it with fire, and then slowly scrape it off.
It's troublesome that only plastic protective film is used on kitchen ventilator. If it were paper, you could use vinegar. Soaking the film with vinegar can make it easy to tear off. Maybe you can try to use gasoline. You said you want to use fire? I think it's better to directly use sandpaper to grind it off. Pay attention to the direction of force when grinding. Do not do it at random. Grind it in direction of left and right or up and down. The grain made in this way is neat and beautiful.
