How to unsync photos from iPhone that were added from a different PC than the one I own?

When I went to upgrade my iPhone 4 to the iPhone 5C, the guy at the Sprint store synced all my photos from my old iPhone through a computer at the store, and onto a new album he so cleverly titled "pics". Now, they're just old and taking up tons of space, and I'd really like to get rid of the 350 photos in there. The problem is, I don't know how I would un-sync the photos from my phone since I don't have access to the Sprint store's computer.

Use this Application "Syncios" is free yet powerful iOS manager which can transfer and vise-versa all types of files between iPhone/iPad/iPod Touch and PC without using iTunes. Its much better than iTunes in terms of user friendliness and performing the task of synchronization.
Download from here: www.syncios.com/