App Storage Size
I have been using the ArcGIS Online Cascade template to create story maps. This template allows images to be used in the story either by linking to an image’s URL or uploading directly to the app. Any image you access, for use in the story, is saved as part of the story and will always be available to use within that storymap.
Recently, while doing some house cleaning in AGOL, I noticed that the file size for some of my cascade storymaps was larger than expected compared to the number of images I knew were actually used in my app, (< 10 pictures or graphics). Upon investigation, I discovered that AGOL Cascade app keeps all of the images that have been uploaded to the story, even if they are not used in your story. This does make sense; as I work to create a story, I often have many different images to work with and am constantly moving them in or out of different sections of the application to find the best story flow.
How to remove them:
Begin editing your Cascade storymap > Choose Add Media. Within the Add Media interface, any image that has been uploaded but is not being used in the app will appear with a delete icon in the upper right hand corner. Click the delete icon to remove the unused image from being stored with the app.
The file size of one of my apps when from 39 B to 15 MB after deleting the unused images.