Follow this to pretty much reset the device:
Go into cmd as admin
Enter diskpart
Now enter List Disk
It should show you your disks present with its capacity. Think about which capacity suits your drive and make sure it is not the main HD.
Type `Select Disk (and the disk no. for your disk. Also shown in disk management)
Enter clean
and exit out of cmd.
Take out your USB and put it in again. Goto disk management and you should see your disk with only unallocated space. Right click on it and select new simple volume.
Complete the on screen Setup.
Good luck
USE DISKPART AT YOUR OWN RISK!