Help! How do I delete photos on my iPhone added from a Windows PC?

Hello everyone,

I have recently added a large amount of pictures from my Windows PC to my iPhone 5C. However, when I came to delete them they had no delete icon, no matter if you selected them, all of them or not! They are stuck on my device!

Is there a way to get rid of them that doesn't involve a system reset? (When I plugged in my phone to the PC it automatically backed up a version with the photos on, so reverting/restoring it won't work, I tried it)

Is there a solution to this?

Thanks,

Henry3324

Info-

iPhone 5C iOS 10.3.2

Windows 10 running iTunes