Automate deleting completed iOS Reminders w/o confirmation prompt.

deleteCompletedReminders.js

// NOTE: to be used with Scriptable + iOS Shortcuts.
// Using this skips reminder removal confirmation prompts.

// uncomment to debug. QuickLook.present(JSON.stringify(args.shortcutParameter));

// expects the Reminder List name.
const argsFirst =
  typeof args.shortcutParameter === 'object'
    ? args.shortcutParameter[0]
    : args.shortcutParameter;
const reminderList = argsFirst;
const cal = await Calendar.forRemindersByTitle(reminderList);
const reminders = await Reminder.allCompleted([cal]);

for (let i = 0; i < reminders.length; i++) {
  let reminder = reminders[i];
  reminder.remove();
}

Script.complete();