What do I need to when selling an iPhone that won't power up in order to remove my information?

If it won't power up why would anyone buy it?

Hello,

The only option to wipe an iPhone without having direct access to said iPhone is through iCloud and Find My iPhone. However, using Find My iPhone to wipe your device requires that your device is turned on and connected to a viable network. Since your phone does not turn on, there is no way for Find My iPhone to remotely access and wipe your device.

Best of luck.