Yes, iTunes will do a full restore.
Connect your iPhone to your computer, launch iTunes, then restart your iPhone holding both Home and power until you see the icon on your iPhone screen to connect to iTunes.
Then, you will be able to completely erase, and restore your iPhone to factory fresh, and the latest iOS (version 9.3.3 is current)
By the way - your poll choices have the same meaning (dunno = don't know)