I think you should be allowed to remove and/or add photos after you have posted a series photos. For instance, you make a mistake and mess up the order you wanted for the series photos. Instagram should allow users to re-arrange the posts without actually deleting the post. Another case may be that you have posted too many photos in the series and see some you don’t like. Instead of deleting the whole Instagram post and reuploading it, you can delete the photos you don’t want. Example: if the original series post had 3 photos but you don’t like the third one any more, you should be able to delete it and that way you will have 2 photos in the series without deleting the actual post itself.