Delete Photos on iPhone synced with Mac

Hi Apple Community! Sorry to bother.

I have an iPhone 12 mini on iOS 16.1 and a 2018 Mac mini on macOS 13.0. So everything is up to date. I do no use iCloud for photos. Instead, I only sync my macOS photos library to the iPhone and I am trying to delete all photos from the iPhone.

It appears to me that iPhone will not allow photos synced from Mac to be deleted directly from the iPhone. (the trashcan icon does not appear below photo). I also tried editing one of the photos and got the message: "This Photo is not editable, Do you want to duplicate it and edit a copy?" So I plugged iPhone into Mac, went into finder, selected the iPhone, went to the Photos tab, and unchecked "Sync photos to your device from..." and then ran the sync process.

Most of the photos got deleted from the iPhone, but there are still 804 remaining and I cannot delete them because they were synced from the Mac so the delete icon is not there.

Thanks for your help!