Here's a few tips I picked up online:
My daughter got white acrylic paint on her purple tank top. I sprayed it with hair spray and rubbed it with a small brush and IT WORKED.
I just removed dried acrylic paint from a freshly modified (2 hours work) camp uniform t-shirt using nail polish remover (scrub/rinse), followed by hairspray (scrub/rinse), followed by Goo Gone (scrub/rinse), followed by SIMPLE GREEN (that was the magic ingredient…No scrub/rinse required). Thank you, Simple Green! It's all clean! Hooray!
Hairspray (extra hold) and pinesol really did the trick.
Hairspray seemed to be most mentioned at various places online.