Press and hold the icons on the start screen, and then drag em to the bottom of the screen to delete icons from the home screen. You can add icons the same way by entering the application menu, and pressing and holding an icon. the screen then returns to the home screen and you can drag the icon to the desired location.

A better way to manage the calender might be adding the calender widget to your home screen. press and hold on an empty location on the home screen, then select widgets and then agenda. Android is as simple as that!