I don´t know the oxygen confirguration for the Jet Blue´s Airbus A320 but for the standard aircraft there is no Flight Attendant Oxygen manual release for the Oxygen passenger mask from their stations.
For dropping "manually" the cabin crew should use the "manual release tool" for each passenger row.
So for dropping all the mask at the same time there is only a switch at the cockpit or the automatic mode due to the loss of pressurization at 14,000 ft cabin preassure.