I’d forgotten how to reformat a thumb drive, so in case I forget again I’m making it the Digital Media Minute tip for the day! Chances are someone else will find it handy.
In OSX, go to Disk Utilities in the Utilities folder (in Applications). Insert the thumb drive into a USB port. Click the white drive icon in the tree corresponding to the name of your thumb drive. Click the ‘Erase’ tab. For Volume Format choose ‘Mac OS extended (Journaled)’ Select the ‘Mac OS extended (Journaled)’ if you’ll use the drive with a Mac OS. Click erase button.
While I’m at it: For Windows, from ‘My Computer’ find the thumb drive you want to reformat (it will have a ‘Removable Disk’ icon). Right click and select ‘format’. In the dialog that appears, just accept the defaults unless you want to change the label of the volume. Hit ‘Start’.
Also, check this freeware method out if you have a need to secure flash drives.