How do I get rid of this photo that keeps showing up at the end of the slideshow? I circled the location so you can see there is nothing there, even though there is a picture that is showing up, and it shows up in the exported version as well. And how do I get rid of all the "yellow" space?
The intrusive image is probably on a lower track which you cannot see in Storyboard mode.
Switch to Timeline mode, clicking the indicated button (1), see image below, and look through the lower tracks, using the slider (2) to move down the tracks looking for the intrusive image and delete it.
The image you've posted is of the Storyboard view, NOT the Timeline view which John asked you to look at!
At the extreme right edge of your image it says "Tiimeline"; click on the word and you will go to it. Then follow John's advice to check for stray items.