Hard Reset HTC Droid DNA

First method:

1. Firstly make sure that Fast boot option in Settings -> Power isn't selected.
2. Then turn off your phone.
3. Press and hold  Volume Down + Power at the same time for a few seconds.
4. Release held keys when you see Bootloader Mode.
5. Then press Volume Down to select option "Factory reset", and press Power button to confirm.
6. Well done!

Second method:

1. Push the Power button to turn on the device.
2. Go to Menu and choose Settings .
3. After that tap Storage and select Factory data reset.
4. Then choose Reset phone, and confirm the whole operation tapping Erase everything.

WARNING !
Hard Reset will erase all of your data
All described operations you are doing at your own risk.