This comes down to the age old answer, " It depends." Depends on what kind of paint is on there and what kinda paint the scope has from the factory.
If it was a rattle can job, you may be able to rub it off with some 90% rubbing alcohol and a rag or denatured alcohol. Then try mineral spirits, then try acetone/lacquer thinner.
Or if you are really cautious, a
kitchen scrub pad and some warm soapy water.