Silly me, I made a reservation at the Sheraton Nuremberg for September booking a member rate flexible cancelation policy, without clicking on the rate details.
Upon seeing the reservation, I now see that it shows cancel 90 days prior to arrival to avoid penalty of full payment.
I then called customer service if there is a grace period to cancel the reservation since I just booked it 30 minutes ago. He put me on hold and came back to me and said the cancelation policy was an error and the property would contact me within a few days.
So I called the hotel and they said they never got a call from Marriott. So I called customer service again to speak with a supervisor.
She told me that member flexible rate doesn't mean the rate is flexible. It could be a non-refundable flexible rate. The term flexible implies not prepaid but paid upon arrival. She also said that there is no 24 hour grace period to cancel my reservation because the rate is cancel 90 days prior to arrival.
So is that what it means? There is absolutely nothing going on in Nuremberg during my stay and the daily rate doesn't fluctuate so much during September and even October.

So take this as a lesson guys, just because it says Member rate flexible, have to click on the rate details to see the actual cancelation policy. It could be 90 days, 120 days, 180 days before arrival because you're SOL as there is no 24h grace period to cancel the reservation.