Use Disk Utility.app to identify the drive number for the desired disk device. Then:
$ diskutil unmountDisk disk<n>
$ sudo newfs_msdos -F 16 /dev/disk<n>
$ diskutil mount /dev/disk<n>
Use Disk Utility.app to identify the drive number for the desired disk device. Then:
$ diskutil unmountDisk disk<n>
$ sudo newfs_msdos -F 16 /dev/disk<n>
$ diskutil mount /dev/disk<n>