code: public void resetContentAndSettings() {
      if (instrumentsVersion.getMajor() < 6) {
        if (hasContentAndSettingsFolder()) {
          boolean ok = deleteRecursive(getContentAndSettingsFolder());
          if (!ok) {
            System.err.println("cannot delete content and settings folder " + contentAndSettingsFolder);
          }
        }
  
        // Wipe the system.log.
        String deviceLogDir = System.getProperty("user.home") +
            "/Library/Logs/iOS Simulator/" + exactSdkVersion + ((is64bit) ? "-64" : "");
        File deviceLog = new File(deviceLogDir, "system.log");
        if (deviceLog.exists()) {
          deviceLog.delete();
        }
  
        boolean ok = contentAndSettingsFolder.mkdirs();
        if (!ok) {
          System.err.println("couldn't re-create: " + contentAndSettingsFolder);
        }
      } else {
        if (!eraseSimulator()) {
          log.info("Erase contents and settings failed on this device: " + deviceUUID);
          tryToEraseSimulator();
        }
      }
    }
docs: Does what IOS Simulator - Reset content and settings menu does, by deleting the files on disk.
  The simulator shouldn't be running when that is done.