How to wipe a USB hard drive
[Author edit] Actually I think the duplicate is this one: Permanently delete files from a flash drive [/edit]
I have a USB stick returned to me by someone else. To maintain confidentiality of what it was used for I want to perform a secure erase on it so that data recovery tools cannot retrieve the contents - I don't know whether the same tools that are used for HDD's can be used on USB sticks, or whether a format will actually overwrite the existing (and deleted contents).
Is there a simple app that can perform this task? Freeware preferably.