You can now set a lead time, during which a particular rate will be unable to be booked on your website or via OTA's. This is an easy way to manage Advance Purchase rates.
From Pricing > Rate plans, select the rate you want to apply this for.
Set your Booking lead time.
The Price plans screen will show a price of 0.00 for the selected number of days, for all room types. (Zero pricing means the room type cannot be booked.)