Electric-vehicle maker Nikola Corp. NKLA on Thursday said that Gerrit Marx, Lynn Forester de Rothschild and Mark Russell were retiring from its board of directors at its annual meeting on June 7. Marx has been on Nikola’s board since 2019, while Forester de Rothschild joined last year. Russell joined Nikola in 2019 as president, became CEO and then retired last year, the company said. “Nikola is focused on delivering results in our core business units of zero-emission trucking and energy infrastructure solutions,” Steve Girsky, chairman of Nikola’s board, said in a statement. “As the Company evolves, the size and composition…