Switch on USB Vcc to enable/disable
That sounds like it'd work, but be bad idea – you simply "brown out" the device, and neither the device (which you don't seem to care about) nor the hub will know what happened, and the behavior of the device while the power is failing slowly (due to residual charge in the capacitors on-device) will be erratical, leading to the hub having to re-enumerate the bus, which might/will lead to a short stop in USB functionality on the other devices. That might or might not be a bad thing. I'd generally avoid it.