Read Write using NffsFile in nRF52832 Bluefruit

Other Hardware Storage
1

Hi,

I am using NffsFile file to write in file in nRF52832 Bluefruit. But its not append text in the file. I am using below code for write in file:

char content1[] = "Test Message MIT |";
        Serial.println(content1);

        if ( file.open(FILENAME_USERS, FS_ACCESS_WRITE) )
        {
          Serial.println("OK");
          file.write(content1, strlen(content1));
          file.close();
        }

and using below code for read from file:

if ( file.open(FILENAME_USERS, FS_ACCESS_READ) )
        {
          Serial.println("READ FILE");
          uint32_t readlen;
          char buffer[64] = { 0 };
          readlen = file.read(buffer, sizeof(buffer));

          buffer[readlen] = 0;
          Serial.println(buffer);
          file.close();
}

So this code is not writing to file. So please can anyone suggest where is I am doing mistake in this code. This code was working fine previously.
Please also suggest how can I remove file from device?

Thanks in advance.