To delete an object, the easiest way is to select it and then press the Delete key on the keyboard. To delete more than one object at once, you can select multiple objects before pressing the Delete key.
You can also right-click the selected object or objects and choose Cut. When you cut an object, it is not the same as deleting it; the Cut command moves the object to the Clipboard, so that you can use the Paste command to place it somewhere else. However, if you cut something, and then never paste it, this is actually the same as deleting it.