Note, the unmount command is umount not unmount.
To unmount a USB Stick you first need to identify it. To do this you need to list mounted drives. From the command line enter:
mount Example Output: /dev/mapper/vg_main-lv_root on / type ext4 (rw) proc on /proc type proc (rw) sysfs on /sys type sysfs (rw) devpts on /dev/pts type devpts (rw,gid=5,mode=620) tmpfs on /dev/shm type tmpfs (rw,rootcontext="system_u:object_r:tmpfs_t:s0") /dev/sda1 on /boot type ext4 (rw) /dev/mapper/vg_main-lv_opt on /opt type ext4 (rw) /dev/mapper/vg_main-lv_var on /var type ext4 (rw) none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw) /dev/sdb1 on /mnt/MEDIA type vfat (rw)
In the above example the drive I need to unmounts is /dev/sdb1. If you mounted the drive, then you should already know what the drive identifier was.
To unmount the drive, from the command line enter: