It is possible to hide a slide when giving a slide show.
Select the slide in Slide Sorted view and select (Tools > Hide Slide).
When you run your slide show this slide will be skipped.
When a hidden slide is next in line a large asterisk will appear in the slide window near the bottom right corner.
You can display the hidden slide by clicking on the asterisk.
You may have to move the mouse slightly if the asterisk does not appear.