How to delete files?

So, I’ve developed an App that records an Audio then display it to the user on a list. The audio has 2 buttons, play and remove, somehow the function removeAudio isn’t working. Am I doing something wrong?

  playAudio(file,idx) {
    if (this.platform.is('ios')) {
      this.filePath = this.file.documentsDirectory.replace(/file:\/\//g, '') + file;
       this.audio = this.media.create(this.filePath);

    } else if (this.platform.is('android')) {
      this.filePath = this.file.externalDataDirectory.replace(/file:\/\//g, '') + file;
        this.audio = this.media.create(this.filePath);
    }
    this.audio.play();
    this.audio.setVolume(0.8);
  }

  deleteAudio(){
    if (this.platform.is('ios')) {
    this.audio = this.file.removeFile(this.filePath, this.fileName);

   } else if (this.platform.is('android')) { 
    this.audio = this.file.removeFile(this.filePath, this.fileName);
   }
  }