If this is before the payment deadline, you can simply log in and change the option on your booking. The option will be removed and you will be refunded the difference or charged if there are any additional fees due to the change.
If it is after the payment deadline, you'll need to inform us by speaking with a member of the team and we'll remove the option from your booking for you, which will update our itinerary. Unfortunately we would not be able to offer any refunds for any unused elements of the booking