When it is so close to the check in date I doubt that the host will accept your request to shorten your stay. The host will need to accept your request - so you can’t shorten the stay alone. When you booked you agreed to the cancellation policy attached to the listing and you will get refunded automatically if you choose to cancel the stay. Remember the host blocked/reserved the place and calendar for you so no one else could book. If I were you I would cancel and ask the host that in case someone rebooks any of the dates - if the host would refund you extra. That is what I offer if a guest decides to cancel that close to the check in date. And cancel as fast as possible as you are currently blocking the calendar so no one else can rebook.
When it is so close to the check in date I doubt that the host will accept your request to shorten your stay. The host will need to accept your request - so you can’t shorten the stay alone. When you booked you agreed to the cancellation policy attached to the listing and you will get refunded automatically if you choose to cancel the stay. Remember the host blocked/reserved the place and calendar for you so no one else could book. If I were you I would cancel and ask the host that in case someone rebooks any of the dates - if the host would refund you extra. That is what I offer if a guest decides to cancel that close to the check in date. And cancel as fast as possible as you are currently blocking the calendar so no one else can rebook.