Deleting an image from your collection is quite simple.
1. Select the Content tool in the gray navigation bar.
2. Click on the Collections tab under the Content header.
3. Select the Images button to get to your image collection.
4. Hover over the Image you'd like to delete, and click on the trashcan icon that appears.
5. If you are wanting to delete more than one photo at a time, do so by selecting each photo (click on each photo's trashcan icon), then choose the red Delete button above the image library.