After you have finished working with a selected section of text, it is a good idea to remove the selection so that you do not accidentally replace or delete the selected section of text. See replacing a section of text for more information.
You can remove a selection using the mouse or the keyboard. To remove a selection using the mouse simply click, with the left mouse buton, anywhere in the edit window containing the selection. To remove a selection using the keyboard simply use the arrow keys to move the text caret.