Flickr is a free photo sharing website which allows you to upload photos into albums that can be then organised, tagged and shared with others. Flickr allows you to delete photos and videos from Photostream. You can delete individual photo directly from the photo page. To delete photo from photo page, open "More" menu which is located above your photos and choose 'Delete this photo' option. Otherwise, you can delete your photo by clicking 'Edit' and then 'Delete' from photostream page. You can delete multiple photos at a time. To do this, gather multiple photos into a batch and perform a batch deletion.
You can install PicBackMan's Flickr uploader for Mac from the website and start backing up photos and videos.