How do I cancel the last day of drop-in visits after booking?

I was booked to do drop-in visits for the last 5 days, but the owner messaged me letting me know they would be home early and do not need me to come in on the last day. I tried to modify the booking but it only gives me the option to cancel the entire booking when I uncheck the day. It is unclear if I would be paid for the work I have done already if I cancel the entire booking. I just want to remove one day and rover has not gotten back to me through support. I don't want to charge the owners for the last day if I don't have to.