Pull out on the plastic plug attached to the bulb the whole bulb will come out, pull apart the plastic adapter to the wire and the wire connector, then attach new and replace.
changing the bulb
the headlight assembly needs to come out in order to replace the bulb.
Yes , according to the 1998 Mercury Mountaineer Owner Guide : ( the headlight bulb is # 9007 )
On some cars you have to replace the whole headlight, but in a lot of cars you replace just the bulb. At the back of the headlight, see if you can twist out the bulb socket. You may depress it while twisting it counterclockwise.
drop the bumper and take the headlight housing out
You replace the bulb the same as a 1998, which is answered further down the page.
the headlight assembly needs to come out in order to change the bulb ive had to do that to my 98 as well.
Replace headlight bulb only when blown.
replace the low beam headlight bulb
See the following site:
On older vehicles you replace the entire headlight. On the newer vehicles you just replace the bulb unless the headlight assembly is damaged.
If you can't get to the back of the light assy you have to remove it from the vehicle and the bulb screws in.