Hi Dusty_Sloth,
Thank you for using Apple Support Communities. I understand you're trying to erase the data on a liquid damaged iPhone 6 that will no longer turn on. I'd be happy to assist.
If your device is unable to turn on there isn't a way to delete the information. That being said there are still some precautions you can take. If your device is still connected to your iCloud account you can go onto iCloud.com and remotely erase the device. Here's a great resource on that process as well as a link to Apple Recycling Programs:
What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch
Apple Recycling Programs
Have a great day.