I am not currently painting, so this is speculation, but for something like this I would use acetone. Denatured alcohol would probably work. I'm guessing rubbing alcohol has stuff in it you don't want.
Can use a paint thinner that is compatable with the paint you are going to use. That is something that you are likely to have around the shop already and it has worked for me for maybe 35 years and running...not all from the same can