The founder of the nonprofit crime prevention group Guardian Angels said he plans to run for mayor of New York City in 2021 “to take back the city” from Democratic Mayor Bill de Blasio. The announcement: “I am the anti-de Blasio candidate. The part time Mayor ‘Dope from Park Slope’ has single-handedly destroyed our city. Roll with Sliwa through the subways & streets & you’ll see why I’m the only one who can #SaveOurCity,” tweeted Guardian Angels founder and radio talk show host Curtis Sliwa. Sliwa, 65 has not yet filed paperwork to compete against de Blasio but has re-registered...