It is not possible to unmount and format the flash drive.

it is impossible to unmount and forge a flash drive writes - The volume on disk4 couldn't be unmounted because it is in use by process 0 (kernel)

Error: -69888: Couldn't unmount disk.

terminal write.

Disk Utility says - Unwritable disk. Checked all security settings. Launched in all applications. Not possible. Yesterday the flash drive worked, wrote a couple of files there and... that's it. Doesn't work. You can throw it away. There is access to the files. But it is impossible to delete them. Help!