You can remove USB devices from a client computer if you do not want those devices to be available to virtual machines.
When you detach a USB device from the remote client, the device disconnects from the virtual machine. Ensure that data transfer is not taking place before you remove the device.
Verify that the devices are not in use.
You might need to use the sync command instead of or in addition to the umount command, for example after you issue a dd command on Linux or other UNIX operating systems.
When you remove the device from the client computer, it is no longer available to virtual machines.