code: public static void removeCustomDeviceData(final String key) {
  		dispatchConversationTask(new ConversationDispatchTask() {
  			@Override
  			protected boolean execute(Conversation conversation) {
  				conversation.getDevice().getCustomData().remove(key);
  				return true;
  			}
  		}, "remove custom device data");
  	}
docs: Remove a piece of custom data from the device. Calls to this method are idempotent.
  
  @param key The key to remove.