Cancellation
In my experience, the only way to solve the situation is to call the hotel. Most times, they will be willing to give you a credit for future stay. The next best thing, if it is an option, is to go directly to the hotel and speak with the manager. I have had this happen many times where I thought I was staying over, but at the last minute had to take off. If you explain to them that it is business that is forcing you to leave early, they are most times generous enough to cancel and give a refund to you.