Help on how to remove case on iPhone 6 Plus

Hello, I bought the "Barely There" case from Case Mate for my iPhone 6 Plus, and the buttons on the side are terrible. So, I've found a new case I want to switch over to. The problem is, I can't get the case off. When I do get it to move, the phone starts to bend. I'm terrified that this phone will break, so I'm not sure what to due.

Any help is greatly appreciated.

Thank you in advance