Marita Rivero is stepping down as vice president and general manager for radio and TV at WGBH, the PBS station announced Friday. Rivero, whose career at WGBH spans 30 years, is credited with creating the global news program “The World,” which airs on 89.7 FM, and “Greater Boston,” “Basic Black,” and “High School Quiz Show,” on WGBH 2. “Marita’s leadership and commitment have exemplified the highest ideals of our public service mission,” WGBH president Jon Abbott said in a statement. “She has an outstanding legacy of service to WGBH and the communities we serve, having led with insight, principle and wisdom in creating programs and launching new initiatives.” Rivero will be succeeded by two members of her staff. Liz Cheng, GM of WGBH’s national digital multicast channel WORLD, will be GM for TV. And Phil Redo, managing director of 89.7 WGBH and WCAI, has been named GM for radio.