|You can get false messages about a USB connected drive, including it's not formatted, if you connect to certain USB ports, or if there is a problem with the wiring to it, or if your power supply is out of whack regarding the 5v the USB requires.|
See response 3 in this:
If you connect the flash drive to a properly working USB port, you should be able to format the drive in Disk Management if it's not physically damaged.
Some flash drives have a tiny write protect switch - you can't format the drive unless the switch is in the position that enables you to.
Windows greys out Delete Partition in Disk Mangement for a flash drive, so by default you can't delete it.
However, you can use something to trick Windows into seeing it as a non-removable drive, in which case you can delete the partition.
I answered a subject about a USB flash drive a long while back, and found a solution, and he found something else, but I can't find it presently.
Try searching on the web, using: "delete partition" "flash drive", and
"delete partition flash drive"
wipe the partition table clean, the linux way:
Some flash drives come with software you install in Windows, or you can download the software from their web site, that you can use to remove (or create, or re-size, or format) the partition.
"How to I remove or resize a partition on my Imation Swivel Pro Flash Drive?
To resize or remove a secure partition, you will need to do the following:
Open the Flash Manager software on your hard drive
Choose Create a partition
Move the slider to zero (0)
You will see a message that your drive will reset to factory settings. All data on the drive will be lost, and the Imation Flash Manager software will reformat your drive to an all public partition. You will now be able to resize the partition."