NoMachine USB drivers are installed on Windows by the Enterprise Client package and by all server packages.

They are necessary to support the forwarding of USB devices such as pendrives inside the NoMachine session.

Instructions below applies to NoMachine v8.
 

How to uninstall NoMachine USB drivers

All steps are mandatory.

1) Run the CMD console with administrator rights:

right click on the bottom left corner on Windows Desktop -> choose Command Prompt (Admin)

2) Move to <NoMachine>/bin directory

<NoMachine> is the directory where you installed the NoMachine software

3) Remove USB drivers and devices from the system by executing from console:

nxservice64  --uninstall nxusb

or, if you are on a 32 bit machine:

nxservice32  --uninstall nxusb

4) USB service will be in ‘Marked to delete’ status until next reboot:

nxservice64  --status nxusb

5) Disable USB in the NoMachine configuration (only for servers)

Skip this step if you have Enterprise Client installed.

Change the following entry in node.cfg, to grant that the nxusb driver will not be loaded after the reboot.
If you cannot edit and save node.cfg, make a copy of it for example on Desktop, apply the requested changes and replace the original node.cfg file with the new node.cfg file.

Run the Notepad (or other text editor) as administrator and open file <NoMachine>/etc/node.cfg

change entry:

#EnableUSBSharing both

to:

EnableUSBSharing none

and save.

Ensure to move the new file to <NoMachine>/etc/, if you have temporarily copied it somewhere else to edit.

NOTE:
Since v8, installing a new package from command line with option to skip USB drivers:

nomachine-packageName_packageVersion.exe /usbinstall="0" /silent
or:
nomachine-packageName_packageVersion.exe /usbinstall="0" /verysilent

will automatically disable USB and set in node.cfg:
EnableUSBSharing none

6) Reboot Windows (mandatory).
 

To check status of USB service, you can run from console:

nxservice64  --status nxusb

This should report: Not installed

How to uninstall USB devices, for Enterprise Client installations before v8. 
This method can be used also for server installations.

1) Uninstall the NoMachine USB device:

1.1 - Run the device manager: Control Panel -> Device Manager
1.2 - Remove all "NoMachine USB Host Adapter" device if it exists.

2) Unregister "NoMachine USB Hub Filter"

   2.1 -  Open Windows registry:  Menu Start -> run -> regedit
   2.2 -  Find the following registry key in the tree on the left:

  2.3. - Find UPPERFILTERS variable on the right side.

      Note : it should contain list of registered filters, but maybe it's empty if no filter is registered.

      Edit UPPERFILTERS variable and remove entries containing nx prefix (e.g. "nxusbf") if they exist.

3) Reboot the Windows machine.

In some cases, it's necessary to make the whole procedure again once the machine has been rebooted.