How to wipe an iPhone remotely without using iCloud?

I'm selling a water damaged iPhone, but i'm afraid that if the buyer repairs it they will have access to all my files that I had, i do not have iCloud so i can't do it through Find My Iphone, and i can't turn the phone on so i can't connect it to itunes or anything.

You can't!

There's only one thing left to try:

Forced recovery mode. Goto www.apple.com/us/support and search "iPhone forced recovery" for instructions on how to do this.

Essentially what it is is connecting your iPhone to the computer with iTunes open. Holding the power and home buttons (like a hard reset) but being connected to the computer puts it in forced recovery. This forces the iPhone to factory default settings. If it doesn't work then no dice.