You can easily delete any unwanted portrait photos in Portrait Auto Flow.
1. Go to the page where the portrait photo is located and select Portraits.
2. Hover over the photo you want to delete and click on the gear icon in the upper right corner.
3. Select Options and Delete Portrait.
4. If you are sure you want to delete this portrait, select I'm Sure.
Note: The portrait will be deleted from all of TreeRing so if you need it again you will need to reupload it.