Select the text you want to change.
Click the Style button near the top of the sidebar on the right.
If you don’t see a sidebar, or it doesn’t have a Style button, click
in the toolbar. If the text is in a text box, table, or shape, first click the Text tab at the top of the sidebar, then click the Style button.
In the Font section, click
, then select or deselect the Strikethrough checkbox.

Tip: You can set keyboard shortcuts to quickly apply a strikethrough or other character styles to text.