https://www.pbainbridge.co.uk/2019/04/dynamically-remove-google-form-options.html

Dynamically remove Google Form options.gs

function appointmentSlots() {
  
  // get spreadsheet data
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var configSheet = ss.getSheetByName('Config');
  var configData = configSheet.getDataRange().getValues();
  var optionsSheet = ss.getSheetByName('Options');
  var optionsData = optionsSheet.getDataRange().getValues();
  
  // get Form Url from spreadsheet
  var formUrl = configData[0][1];
  Logger.log('formUrl is: ' + formUrl);
  
  // open Form
  var form = FormApp.openByUrl(formUrl);
  
  /* create emtpy array to push only available Options into for
  updating Form */
  var options = [];
  
  
  // loop through available slots and push into array *************
  var optionsDataLength = optionsData.length;
  for (var i=1; i<optionsDataLength; i++) {
    
    var choice = optionsData[i][0];
    var left = optionsData[i][2];
    
    // check if slot not blank and the option available (not been used)
    if ((choice != '') && (left > 0)) {
      options.push(choice); // add to array
    }
    
  }
  // end of loop through available slots and push into array ******
  
  
  // set item type to Multiple Choice for accessing Form Options
  var formList = FormApp.ItemType.MULTIPLE_CHOICE;
  
  // access Form Options list
  var formItems = form.getItems(formList);
  
  // access first list on Form and rewrite all options to ones that are available
  formItems[0].asMultipleChoiceItem().setChoiceValues(options);
  
  
}