Code.gs

function doGet() {
  try {
    const savedConfig = PropertiesService.getUserProperties();
    const triggerId = savedConfig.getProperty('TriggerId');
    if (triggerId) {
      Logger.log("Looking for triger", triggerId)
      let t = ScriptApp.getProjectTriggers();
      for (let trigger of t) {
        if (trigger.getUniqueId() == triggerId) {
          Logger.log("Removing trigger", triggerId, trigger);
          ScriptApp.deleteTrigger(trigger)
          break
        }
      }
      savedConfig.deleteProperty('TriggerId')
    }

    Logger.log("Creating new trigger")
    const newTriggerId = ScriptApp.newTrigger('triggerFunction')
      .timeBased().everyMinutes(15)
      .create().getUniqueId();
    Logger.log("New trigger", triggerId)
    savedConfig.setProperty('TriggerId', newTriggerId);

    return HtmlService.createHtmlOutput(`Trigger ${triggerId} created`)
  } catch (e) {
    Logger.log("Trigger stuff failed", e)
    return HtmlService.createHtmlOutput(`Trigger stuff failed ${e}`)
  }
}

function triggerFunction(event) {
  try{
    Logger.log(event);
  } catch(e) {
    Logger.log(e);
  }
}