Fire Department brass ordered an East Village ladder company to remove its “red line” American flag honoring the squad’s six brothers killed on 9/11 – after a neighborhood resident complained it was “fascist” and a local lefty pol questioned whether it was a “politically charged symbol.”The shocking order came March 22 after a man claiming he was a staffer for Democratic Manhattan Councilwoman Carlina Rivera confronted firefighters at Ladder Co. 11, sources said.The man pedaled up to the East 2nd Street firehouse on a bicycle and told firefighters he worked for Rivera and that the councilwoman’s office “complained” to the...