How to delete 'My pictures' photos?

How do I delete the section on photos entitled 'My pictures' which has photos taken off of my computer by accident. When I try and delete them normally by going on the edit option then selecting it them delete it doesn't work, it also doesn't work if I go onto the photo and try clicking the trash can to delete it as it is not there. My phone (IPhone 4s) allows me to delete other photos but not the ones taken from my computer:/

Anyone know how to delete them?

Are you talking about photo stream? If you want to delete all of them just disable photo stream by going to Settings >Photos(or photos and camera) and where it says "my photo stream, just disable!"

If you want to delete a specific photo go to My pictures on your computer and move that photo or delete it from your computer, Sync your iPhone with iTunes and it will not sync that photo so it will be deleted from your iPhone. If you have iOS 7 you go to your folder and say select choose the photos and click delete.