Q: how to delete photos uploaded from windows pc

You need to use iTunes to delete photos that were placed onto the phone by syncing from a computer. The instructions below are quoted from Sync photos to your iPhone, iPad, and iPod touch in iTunes - Apple Support

Delete synced photos

1. In iTunes, locate and click on your device.
2. Click Photos.
3. Choose "Selected albums" and deselect the albums or collections you want to delete.
   To delete all synced photos, deselect "Sync Photos from" and, when asked, click "Remove photos."
4. Click Apply.

Learn how to delete photos and video synced from iTunes when you can't access the originals.