Just scrape it off with a razor blade. You can get "safety" blades that are
one-sided, and you can also get a refullable holder for the blade. I keep
it in my desk and use it to scrape off Mod Podge, acrylic paint, ink, and
dried clay. By scraping tables before cleaning, you wash up job is often
made easier. For example, if clay is scraped off first, you avoid the muddy
mess that a sponge makes.
I teach high school so I can trust kids to do this. Usually there is one
kid who reallly LOVES this process, and once given the opportunity, (s)he
goes scrape-crazy and cleans the whole room. It's hard to stop.