Two misdemeanor charges against Roy Brown, former principal of the Wadsworth Avenue Elementary School who was accused of failing to report to police allegations that a 7-year-old pupil had been molested, were dismissed by Los Angeles Municipal Judge Susan Isacoff. The city attorney's office told Isacoff the case should not go forward "in the interest of justice," the judge's clerk said. When the case was filed in February, City Atty. James K. Hahn said Brown became aware in late November of allegations that a 7-year-old girl had been sodomized by an 18-year-old youth at her home, but failed to notify authorities. It was not until January that a school psychologist told police of the allegations.