@Jackie132:
If you have set in your admin panel the maximum number of nights that can be booked at a time, then there is no need to worry about the monthly rate showing as the system will not let the guest book it anyway.
1. Go into your admin and click on your listing, navigating to the settings screen. Click the "Availability" link. Scroll down to trip length and set the maximum nuber of days to 14.
2. Next click the "Pricing" link and make sure the monthly discount box is empty.