Emmett Dulaney of campustechnology.com has posted an article on how to properly dispose of old flash drives, citing the value of the information that can be stored on a drive as a primary reason to properly destroy your old flash drives.
You may think deleting the files on the drive via your computer completely erases all traces, but this is not the case.
“Deleting the files isn’t a good solution since what actually gets deleted is the reference to the file–the data still remains until it is overwritten.”
For securing your data in future, Emmett recommends IronKey.
“IronKey markets a line of flash drives secure enough for sensitive government use and more than sufficient for what most people are trying to protect. A password must be given to access the data and if you give the wrong password 10 consecutive times, the unit self-destructs. The case is waterproof and tamper-resistant: if you break it open, it self-destructs.”
You can read more at campustechnology.com