Running out of ideas - how to delete all photos on my iPhone appearing to be a leftover from the icloud migration in Photos? I currently have an iPhone 8 with 256 GB storage which I migrated my previous iPhone SE 1st edition with 64 GB storage to when I got it from an iTunes backup and reused the SE for other purposes.  I also have a lot of photos which I originally kept in Photos on my Mac and used Photostream to automatically copy new photos to my iPhone.   At one point I transferred my photo library (50000 photos and videos) to iCloud and did as prompted and it has worked well for me.
Now I broke the glass on the iPhone 8 so I need to send it in for repairs (corona prohibits walk-in repairs) which may take several days, so I would like to do the &quot;backup to itunes - restore backup on reset device keeping passwords and everyting&quot; exercise again but this time back to the iPhone SE
Unfortunately iTunes refuses to restore the backup as the device is too small.  Investigations show that photographs take a lot of space (see image) even after turning iCloud off on the iPhone 8 and then trying to synchronize from my Mac again with just a single album containing a single image.  Didn't get rid of them.
I cannot delete the Photos app so this cannot get rid of the data.  I can attach a bluetooth keyboard but the Apple-A command doesn't select all the images for deletion.  I can run xcode on my Mac against the 8 if necessary.
Is there a way to remove the Photos other than one at a time?
It turned out when connecting with cable and starting Image Transfer that the Camera Roll on the iPhone contained 38.000 photos (which I suppose somehow happened during my Photos-on-Mac -&gt; iCloud migration last year).
The Image Transfer program could delete them all but it took a few hours, and the backup size shrunk as expected to be small enough.
The &quot;Hey you have a new iPhone next to this one&quot;-transfer from the old iPhone to the new could then complete as expected.