You can delete images from your already created slideshow. Follow the steps to do so:
1. Select the slideshow which you want to modify, and then click ⛭ to open slideshow properties.
Tip: You also can delete images by clicking Element settings on the properties toolbar.
2. Hover the pointer over the image you want to delete, and then click X.
3. When you're done, click the Update button and save your page!