Question about Crayola Ultra Clean felt tip pens with cone tip

If you want to decorate the windows with it, probably not the best choice. The come off easily but are not made for glass surface so you won't see your art in bright colors. If you're asking if it comes easily if accidentally used on windows, then yes the can be swiped of with a wet towel.

You can paint on the windows and the paint can be easily removed. But: it has little covering power on the windows, so oily colours are better, especially for the windows.

I have no idea, I haven't tested it on windows. I know it can be used on textiles, but I don't think it can be used on windows.