How can I format the text with “strike through”?
You’ve got a few options.
Select the text you want to strikethrough, then either:
Format > Font > Strikethrough
Or Ctrl + Shift + -
Or you can do what I did, and add the strikethrough button to your Format bar.
Tools > Customize Toolbars
Then you just have to press a button. 
HTH,
Jim