The Army announced it is closing and demolishing a child-care center at its base at the Presidio after allegations that as many as 60 youngsters were sexually abused there. Gary Willard Hambright, 34 years old, a former worker at the center and a former Southern Baptist minister, has been charged with abusing 10 boys and girls there. He worked at the center as a civilian employee for 18 months. A Federal grand jury in San Francisco spent 10 months investigating abuse allegations surrounding the Presidio center, and almost 100 children were examined for physical or psychological signs of sexual abuse. At least four children were discovered to have chlamydia, a sexually transmitted disease. An assistant United States attorney, Peter Robinson, said Mr. Hambright was charged with molesting only 10 children because other victims were so young they would not be allowed to testify in court. More than 70 children had been interviewed by Army therapists as potential abuse victims. Parents have said as many as 60 children were molested at the center. A 16-member Army review team recently inspected the Presidio center as part of an investigation of the almost 300 child-care centers run by the Army, which care for an estimated 94,000 youngsters daily. Allegations of sexual abuse have surfaced at more than 10 percent of those centers since 1984. Among them are the centers at Fort Dix in New Jersey and the United States Military Academy at West Point.