Hey.
I would recommend an acrylic paint, like the ones used for a model kit or Warhammer. They're nice as you can just wash your paintbrush and hands with plain water.
If you want to get them cleaned before trying paint, you can try alcohol 96-98% (the type you get in a pharmacy, not the kind you drink). Not sure if it will work though, depends on what type of paint was used.
PS - Welcome to the board!
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