Q: No way to delete synced photos from iPad?

Try syncing Photos again in iTunes, but just select an empty folder.  This should overwrite whatever previously synced photos there are.

If the instructions in steps 1-4 of the instructions below from Sync photos from your computer to your iOS device using iTunes - Apple Support aren't working, try the method in the "Learn how to ..." link that is shown below step 4:

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.

You're welcome!