Painting miniatures is fun, but cleaning them can be quite frustrating, especially if you're dealing with many parts. The easiest way to remove any unwanted paint (or color) on the plastics is by using an eraser or toothpick since they are a similar consistency compare to modeling putty. When removing paint from plastics, always remember that too much rubbing will result in scratches and marks, so use the erasers lightly and only apply light pressure when needed. If there's excess paint around the details, try using some of your thinners for this rather than water, as it may help lift it off more effectively. An alternative way to do this would be by soaking the part overnight in odorless thinner, waiting for the paint to loosen up and then gently scrubbing the affected areas with an old toothbrush. Once we're done, clean them thoroughly with water and let them dry before using your model again. To avoid this in the future, make sure that any time you work on a project is always spent painting and not cleaning. This way, it will be easier to wash away what's leftover from the paints after working on them.