Delete-All-Slides-Notes

function clearNotes(){
  var presentation = SlidesApp.getActivePresentation();
  var presentationId = presentation.getId();
  var slides = presentation.getSlides();
  
  var requests = [];
  
  slides.forEach(function(slide, i) {
    var slideNote = Slides.Presentations.Pages.get(presentationId, slide.getObjectId()); 
    var slideNoteId = JSON.parse(slideNote).slideProperties.notesPage.notesProperties.speakerNotesObjectId;
  
    var slideNotesPage = JSON.parse(slideNote).slideProperties.notesPage;
    var shapeText = slideNotesPage.pageElements[1].shape.text;
    
    if(shapeText != undefined){
      requests.push({
         deleteText: {objectId: slideNoteId,textRange:{type: 'ALL'}}
      });
    }
  })
  
  if(requests.length > 0){
     var batchUpdateResponse = Slides.Presentations.batchUpdate({requests: requests}, presentationId);
  }
}