For a professional look...
Buy a second switch from eBay.
Leave the 'real' switch connected, but hidden behind the door card (if you don't, control from your side won't work any more)
Install the new 'fake' switch into the door card, which, of course, now does nothing at all.
Half-assed approach...
The same could be achieved by cutting and joining some of the wires behind the passenger switch, but you'd need some wiring diagrams or spend a fair amount of time with a multimeter. You can't just 'do away' with the switch, it won't work from your side.
What car is it? You might be able to buy just a switch (i.e. easy to cram behind door card), or might need to buy it with the black plastic surround.