In such case, please go to your iPhone's Bluetooth settings, click on your Monimoto device and choose 'Forget the device'. Reset the Monimoto device by connecting it to USB charger or Laptop/PC as shown in this video. If you have a new device, simply hold the small button next to the SIM card for 3 seconds.
In Monimoto app - create a new account by providing your phone number and entering the confirmation code. Then pair Monimoto with your phone like you did during the first setup.