Add a control you don't want - to find out what happens when you make a mistake! For example, add a checkbox by selecting that icon from the toolbox and clicking somewhere on the form, away from the buttons.
To delete a control follow these steps:
It is as simple as that!
A second way is to right-click on a control. Try this. There are quite a few options here, amongst which, in the second block of menu items, is "Delete control". This has the same effect as the previous action.
At any point you might want to stop following the tutorial and pick it up again later. So you need to know how to save your work for later recovery.
Go to the "Project" menu and select the "Save as" menu item (F12 is a useful short-cut). This gives you the same "Save as" dialog that you see every day. The IDE pre-selects a filetype ("Project" - extension prj) and invites you to offer a name. I have called my example "Example1".
Subsequently you could use the "Save" menu item (accessible via the Windows standard Ctrl+S) and the IDE will save the project in the same name (i.e. over-write the earlier version).
Next we shall make our example do something by writing our first event code.