This is a small modification on CHIP computer that allows to power off the USB port.

As seen in the schematics, U15 supplies power to the USB port. U15 is enabled by a pull-up resistor (R86) on pin 4.

By soldering a wire on U15 Pin4 and connecting it to a GPIO port like XIO_P0, USB power can be controlled by software.

fordsfords has a nice GPIO control library for bash on Github

git clone https://github.com/fordsfords/gpio_sh.git
cd gpio_sh
source gpio.sh

Set port direction

gpio_export XIO_P0
gpio_direction XIO_P0 out

and then use:

gpio_output XIO_P0 0

to power off USB

and 

gpio_output XIO_P0 1

to bring power back.