What take acrylic paint off of windows?

Not easily, but it will wash off. I use a glass palette to mix acrylics on and I have used acrylics to paint temporary work on Windows and mirrors. For the palette, either wash immediately after use, while the paint is still wet, or let it dry and peel it off. For Windows and mirrors, I use a razor scraper for small areas and a soft bristle brush (nylon) and hot soapy water for large areas.