If I remember, it's a D1S bulb for my 2012 SX, but please verify the specific bulb for your 2015.
It's a challenge to get to the bulb, but there are helpful procedures. You can use a tiny screwdriver bit, like the short kind that fit on the end of those swappable screw drivers. That will fit in the extremely short space behind the dust cover, so you can remove the screw of the dust cover. Hopefully you have a wrench or pliers to turn the bit without using the screwdriver handle.
Under the dust cover, there is a clamp holding the old bulb in place. That takes some muscle to unclamp. Then disconnect the cable connector on the back of the bulb, and you should then be able to remove the old bulb.