While doing some trial-and-error I managed to flush all photos form the "Recently Deleted" folder iOS 9:
1. Settings > iCoud > Photos > UNCHECK the "iCloud Photo Library";
2. Check in your Photo ap on iPhone if the number of photos in the "Recently Deleted" folder are decreasing (mine counted over 11k);
Et Voila! All photos deleted!
3. Settings > iCoud > Photos > CHECK the "iCloud Photo Library" back to ON again;
4. Turn off your iPhone;
5. Reboot your iPhone and all should be working, problem solved and freed up and reclaimed the 1.5GB with the deletion of the "Recently Deleted" folder!
BEFORE:
AFTER!: uploaded some new photos, so the usage is now 931 MB.
6. To be sure of the deletion, I deleted the "Recently Deleted" folder also via the browser iCloud ogin!
I hope some of you may be helped with this post!
Cheers
1. Settings > iCoud > Photos > UNCHECK the "iCloud Photo Library";


2. Check in your Photo ap on iPhone if the number of photos in the "Recently Deleted" folder are decreasing (mine counted over 11k);


Et Voila! All photos deleted!

3. Settings > iCoud > Photos > CHECK the "iCloud Photo Library" back to ON again;

4. Turn off your iPhone;
5. Reboot your iPhone and all should be working, problem solved and freed up and reclaimed the 1.5GB with the deletion of the "Recently Deleted" folder!
BEFORE:

AFTER!: uploaded some new photos, so the usage is now 931 MB.

6. To be sure of the deletion, I deleted the "Recently Deleted" folder also via the browser iCloud ogin!


I hope some of you may be helped with this post!
Cheers
Last edited: