How to delete photo album on iPhone 5c?

I synced a folder of pictures from my computer onto my iphone 5c. So now my albums are "Camera Roll" and "Folder" I want to remove the Folder one because I don't want those pictures anymore. I went on iTunes and removed that folder from being synced but it wont delete off my iphone! Help!

I have an Ipod 5 and all i do is click trash.