Transforming a string into another string with lowercase letters and deleting spaces from the origin

//ARDUINO C++
//Transforming a string into another string with lowercase letters and deleting spaces from the original string
void setup()
    {
      Serial.begin(9600);
      String inputString = "Pro TV HD"; //stringul initial
      // Transformarea in string fara litere mari si fara spatii
      inputString.toLowerCase(); // transforma literele mari in litere mici
      inputString.replace(" ", ""); // elimina toate spatiile din string
      Serial.println(inputString); // rezultatul afisat va fi "protvhd:
    }

void loop()
    {
        // loop
    }