This simple board plugs inline with a USB cable. It always passes the 5V power and normally passes the USB data signals. But when you press the button, the USB data signals are momentarily disconnected.

For the last few months I’ve been developing a USB Host Library for powerful but complex EHCI USB port in Teensy 3.6 [..] Reaching over to physically unplug the USB cable gets old quickly! Really, really old, both hands off my keyboard… right when trying to focus [..]  I made this handy little board with a proper USB 2.0 high speed mux chip. The control signal is just 3.3V logic, so I might even wire it up to something to automate the process.