To turn off the highlighter, press the Esc key.
Also…
Turning on highlighting—versus the usual one-time use—is nice when you are highlighting a lot of text. Before you highlight text, click Home, thenclick the arrow next to Text Highlight Color, and then click the color you want.
When the highlighter is turned on, notice the mouse pointer looks like this
when you place the mouse pointer on any text. To turn off the highlighter, press the Esc key.