elcome to fdisk (util-linux 2.27.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

/dev/sdb: device contains a valid 'iso9660' signature; it is strongly recommended to wipe the device with wipefs(8) if this is unexpected, in order to avoid possible collisions

Device does not contain a recognized partition table.
Created a new DOS disklabel with disk identifier 0x81900676.