HELP TO UNINSTALL!!!

[wemerson...@gmail.com]

I installed the latest version of OS in my pen drive 8GB, but the system did not boot on my PC and now I want to uninstall. I can not, because it has no file inside the pendrive, and the current total memory it is 1GB. How can I delete the system and return my pendrive for 8GB? 
Thanks!

[marten...@gmail.com]

Just delete all partitions on the disk and fill sectors with 0 or use USDoD 5220.28-std