You're talking about the brake (not "break") rotor. I agree with Monster Pete. Any paint on the braking surface should have been scraped away by the pads. Whatever paint is left, just scrape it away using steel wool or sandpaper. Clean the rotor using isopropyl alcohol.
Possibly you will need new brake pads. The paint might have contaminated your pads. Those aren't so easy to clean. Test the brake as Monster Pete suggested. If it stops you like it should, then no worries.