I'm not near my RTV right now but traditionally and in most applications, there's either 2 "pinch" tabs (that need depressed) or a spin-on nut on the back of the plug and then for both cases, you push the lighter towards where you plug into (in your case, into the passenger compartment).</p>
Not sure where the wiring connectors are but you may need to do some splicing if you're moving it.</p>