removing a file from the show

where does it go when I remove a photo? Can I reinsert?

Based on the subject title, I’m assuming you mean removing a “photo” (not a “file”). Removing a photo from your slide show does not remove it from the folder in which you originally accessed it from. It’s still there. Yes, you can reinsert it anywhere else you would like – just click and drag it to where you want to place it.