Thanks for reporting the switching to Celsius issue. Apparently devices in the US have had a tendency to switch back to Fahrenheit when opening ForecaWeather 0.9.4. A fix for this bug will be released soon.

To get rid of extra cities, just search for others and they will be pushed off the list. In the fullscreen program, clicking the title bar also allows you to open previously visited places. If you visit 4 favorite places from there, any others will disappear from the buttons one by one.

The previously visited list can contain 50 cities so most likely everything viewed in the application will remain there, but they shouldn't get in the way being hidden in that menu.