You can slide the calendar as was suggested or you can go to your calendar, click to open the left side menu where you would add your description and other property details and look at the bottom. There is a little box that shows your property as "Listed." Click that box and click "Snooze." When you do another box will pop up asking you to enter the dates to start and stop. Doing it this way, as opposed to sliding the dates, has a drawback, however. This method will remove your listing from showing in the search results completely. Sliding the dates will allow it to show so people can still book now for next summer but not during the time you have blocked.