Originally Posted by VegasGambler

Award stays are fixed price so they are very lenient when it comes to this. Theoretically the standard room can have minimum stay or similar restrictions but they will generally look the other way and do it for you anyway. Some people abuse this.

If you are on a paid stay it's a little different. Technically the agent can't just remove nights but I was in a similar situation in the past. The agent (globalist line; I didn't have a concierge at the time) noted that cancelling and rebooking for one fewer night would cost more then just paying for all the nights. She said that she would put a note on the res so I could just check in one day late. I asked if she could contact the hotel about removing the first night without repricing everything. She put me on hold and called them, and the hotel agreed to do that, so I kept my booked rate but only paid for the nights I stayed. This was well after the cancellation deadline too -- I called from SFO after I was unable to board my flight (the hotel was the HR Tokyo)