How to disable a USB port

For our RF Test Positioner System (illustrative example) I need to add a software-controlled fan. I would like to add a fan like this and simply tu off it's USB-power to tu the fan on & off.

Need

• A method to tu the USB source power for this fan on and off

Question

• How can you disable the power of a USB port? Is there special USB hubs or devices?
  • I have found mechanical switches, but I am looking for software-controlled! :)