The disk "Flash Player" is still attached to the filesystem. Go into
/Volumes, and you should see it there. There are two ways to proceed, the GUI method, or the command line method. Use whichever you are most comfortable with.
GUI: Navigate to
/Volumes and press ⌘ Command+E. This will eject the volume.
diskutil eject /dev/diskx, in this case
disk35. This will also eject the volume.
The difference between
diskutil unmountDisk and
diskutil eject is that
unmountDisk only ceases disk-IO between the disk and the filesystem, but keeps it attached so that it can be mounted later. However,
eject effectively 'removes' it from the filesystem, and remounting it may involve physically reconnecting the disk. Think of them as "stand by" and "shutdown" respectively on a computer.
Eject a disk. Media will become offline for the purposes of being a data store for file systems or being a member of constructs such as software RAID or direct data. Additionally, removable media will become eligible for safe manual removal; automatically-removable media will begin its physical (motorized) eject sequence.
Unmount an entire disk (all volumes). Force will force-unmount the volumes (less kind to any open files; see also umount (8)). You should specify a whole disk, but all volumes of the whole disk are attempted to be unmounted even if you specify a partition.