I learned today
How to Format a Flash Drive in Linux. You must have sudo or root privileges.
# Make sure the drive is mounted.
> sudo mount /media/usbdisk

# Find the file system type and Filesystem (/dev/xxxx)
> df -Th
Filesystem    Type    Size  Used Avail Use% Mounted on
...
/dev/sdc1     vfat    126M   12M  114M  10% /media/usbdisk

# Unmount the drive.
> sudo umount /media/usbdisk/

# Use mkfs to format the drive.
>  sudo /sbin/mkfs -t vfat /dev/sdc1
mkfs.vfat 2.8 (28 Feb 2001)

# Mount the file system and check the size.
> sudo mount /media/usbdisk/
> df -Th
Filesystem    Type    Size  Used Avail Use% Mounted on
...
/dev/sdc1     vfat    126M     0  126M   0% /media/usbdisk

Good luck.