I added a text slide to a slideshow. I can't get rid of it. If I delete it, the neighboring picture gets deleted, too. If I re-add the picture, the text slide reappears with it.
The Title slides in iPhoto work in an odd way. When you create a title slide iPhoto uses the first photo as the title and then puts text over it.
So when you delete it you are deleting the photo with the text on it.
To remove the text click on the photo, and in the settings pane, uncheck Show Title Slide'.
If you want to add a proper title slide it is better to create it in PowerPoint, Keynote, Paint, Photoshop etc, and save as either a JPEG or PDF and import that as a photo into iPhoto.