Open your Google Slides presentation and select the text you want to strikethrough.

Click on "Format" in the top menu.

Select "Text", then click "Strikethrough" from the dropdown menu.

The selected text will now have a line through it.

To remove strikethrough, repeat the steps and click "Strikethrough" again.

Alternatively, use the shortcut: Windows/Linux a) Press Alt + Shift + 5 Mac b) Press Cmd + Shift + X.