If you long press on a blank spot on the home screen you should get to the screen to add a Widget.
scroll thru the list of Widgets till you find the new calander Widget and you press and hold on it till it allows you to drag it to where on your home screen you want to park it.
Widgets are programs that run constantly in background so are different from the usual desktop shortcuts.
When you want to remove one you just long press on it and drag it to the garbage can that appears
The clock,Weather and some other advertising blocks are part of the Samsung Launcher and can only be removed by installing a different LAUNCHER but you would have to pick what apps and widgets you want piece by piece to put on your screen all over again.
I perfer Zeam launcher beacause it is simple and doesn't require ridiculous PERMISSIONS that open you up to hacking.
Calanders and schedules are usually a Widget as they need to run in background to do there job