How to output 0V for an input of 6V
to play it safe I must generate 0v and 5v to the IN pin of the IC.


No, because on a low supply you'll be likely destroying the device. The recommended operating conditions state that Vin should be between 0 volts and Vcc.

So, use a pull-up resistor (to Vcc whatever that is) and a MOSFET or BJT to drive the IN pin. There will be signal inversion so be aware of that. It's called an open collector or open drain circuit and the pull-up (1 kohm to 10 kohm) automatically fulfills the voltage level requirements set out in the data sheet: -